LMS-2194

The wrong permission was being checked for pinning/unpinning, so a
sufficiently clever student could pin and unpin threads.

JIRA: FOR-499

JIRA: FOR-523

STUD-1140

JIRA: FOR-470

Some messages generated by the comments service are not readily
translated because they come from third-party libraries. Thus, we plan
to try to avoid showing any comments service generated message to the
user. This check preempts the only end-user-visible CS-generated error
message that we are presently aware of.

The front-end code for rendering a thread always makes an AJAX request
for the resopnses, regardless of how the thread was accessed (directly
by URL or by selecting it from the thread list). Previously, when
a user accessed a thread directly by URL, the LMS would initially
request the thread from the comments service with responses, but that
response data was never actually used. Now, the responses are not
fetched with that initial query.

This code adds the ability to add Mako template lookup directories on
the fly, allowing third party add-ons to contribute their own Mako templates.
A new API function for registering Mako templates is introduced::

    from edxmako import add_lookup

    add_lookup('main', '/path/to/templates')

    # Or, specify a package to lookup using pkg_resources.  This will
    # add the 'templates' directory inside the current package:
    add_lookup('main', 'templates', package=__name__)

fixing unit tests

fixing merge error

fixing xqueue submission issue with unicode url (trial 0.1)

fixing fotmats as commented upon

removing yaml file language selection

Unicode changes to support QRF

removed unnecessary pass in modulestore/init.py

fixing merge error

fixing fotmats as commented upon

removing yaml file language selection

fixing pep8 violations

- fixing pylint violations

pylint violation

fixing line spaces and formats

ignore pylint E1101

remove empty line

fixing pylint violations

 pep8 violations

bulk mail unicode/decode

fix migration error

fix pep8 just to push again

more unicode/decode
Final changes to comments and error messages.

The relevant parameters and data are merely passed through between the
front end and comments service.

If this management command fails it's tough to figure out why without
seeing the text from the exception.  Luckily comment service does
return useful feedback, we just have to show it.  This one-line
change just add the exception text to the error message.

Before (with spurrious debug msgs removed):

    sefk@util1:~$ ./manage.sh reload_forum_users Anthonyhubendurance
    update user info to discussion failed for user with id: Anthonyhubendurance

After:

    sefk@util1:~$ ./manage.sh reload_forum_users Anthonyhubendurance
    update user info to discussion failed for user with id: Anthonyhubendurance, error=u'["Email is already taken"]'

No unit testing (sorry) added since this doesn't have coverage
already, and it's just a simple error case.

JIRA: FOR-398, FOR-399

STUD-1072

Part of STUD-1030

This button has been broken for at least a year, so the code has
suffered from bit rot and should be reimplmemented if the feature is
necessary in the short term (which is unlikely since it has been broken
for so long).

The motivation for this change is performance. The forums UI code gets
the list of users for each role and renders the staff label based on
those lists. The list for the staff role is expensive to compute because
there is no index on the is_staff attribute, and we cannot create one
because the User model is built into django.

Users with is_staff=True are still assigned the Moderator role upon
enrolling in a course, so this change will have no practical effect
except that a user who is granted staff privileges after enrolling in a
course will have to be made a Moderator in order for their posts to be
labeled.

Additionally, the UI did not use the list of users with the Student
role, so that list has been removed as well.

Avoid recomputing course module information for every thread, which
should dramatically improve the performance of high-percentile latency
queries.

JIRA: FOR-250

The _DISCUSSIONINFO global was originally used as a cache, but has since
lost that capability and is therefore just harmful. This is a precursor
to more refactoring that will improve the performance of the forums and
may itself provide some performance improvement because it separates the
computation done by two functions that each previously computed the
entirety of _DISCUSSIONINFO.

This is in preparation for significant refactoring of the code in
question.

CommentClientError now has sane subclasses that are meaningfully
distinct, and each subclass is handled appropriately. Errors raised by
the requests library are no longer handled by turning them into
CommentClientErrors, since there is no meaningful handling we can do,
and this way we will get more visibility into why errors are occurring.
Also, HTTP status codes from the comments service indicating client
error are correctly passed through to the client.

Logging the duration of each request will allow us to determine
whether there is a significant difference in the latency reported by
the comments service and that observed by the LMS. Each request will
be assigned a unique identifier to allow correlation of the reported
latency on each end.