Fix Video Player Initialization Issue

Cleaned pylint quality issues in instructor email content history code

Refactor ADVANCED_COMPONENT_TYPES

Added clarification for events that do/not include session values

    Modified to a setting in CMS common.py and aws.py
    Also factored out are: ADVANCED_PROBLEM_TYPES

    This enables third parties to add XBlocks to their system
    without having to make a code change.

    Code also added to ensure that a component should exist in both
    ADVANCED_COMPONENT_TYPES and the course advanced module list
    in order for it to be enabled in the course.

Instructors can view previously sent email content

Annotation Tool: Fixed Flagging for Instructor flag removal

Previously on the send email page of the instructor dashboard, instructors could only view
task information about emails they've sent for their course in the past.
In addition to this, I've now added the ability to see the content of all previously sent emails.

A "Sent Email History" button has been added to the page. When clicked, a table displaying the
subject line, number of emails sent, and date/time of submission for each previously sent email
is created. An instructor can then click on any subject line to see the content of that email,
displayed in a modal window that appears on the page.

The window is also equipped with a "copy email to editor" button, which copies the emails contents
to the tinyMCE editor, so that an instructor can easily resend an email that they've sent
in the past.

Annotation Tools: Added lots of comments, fixed spacing, fixed slice issue

Annotation Tools: i18n fixed for this tool

 - fixed Translator to Translators

Annotation Tools: Removed unnecessary class and worked with element object

Remove duplicated data from legacy events

Sarina/080414 translation update

Remove tooltip manager to get tests working in CMS again.

Revert "bok-choy: check mysql the old way."

Translate string iff non-empty

Basic notifications handling.

numbering error

Ahodges/documentation/doc764

Revert "allow rsyslog to be none"

bok-choy: check mysql the old way.

LMS-11163

Add possibility to remove group configurations. 

Bok-choy: check if mysql is running, even if it's not a daemon.

allow rsyslog to be none

This resolves an issue where a checklist's long_description being empty
caused gettext to dump PO file headers.

I had originally made this change to the Stanford-Online/edx-platform
repository a few weeks ago [0] to address a failing test on our fork.
I didn't take the time to diagnose the root issue; I just fixed it for
the single case.

After stumbling across the issue elsewhere, @kluo <kevkluo@gmail.com>
followed through and tracked down the cause of the behavior. It turns
out that `gettext`, by default, translates the empty string into PO file
headers; this is apparently a feature, not a bug [1].

This behavior seems counterintuitive; for our use, it seems that
translating an empty string should simply return an empty string. We
already program defensively around this in platform code [2], but it'd be
convenient to resolve this with a centralized solution, instead of a
patchwork of fixes.

[0] 4b88f54a
[1] http://stackoverflow.com/questions/18459387/translation-of-empty-string-shows-po-header
[2] https://github.com/edx/edx-platform/blob/master/cms/djangoapps/contentstore/views/checklist.py#L140

The impetus is integration with test environments, where mysql is not configured
as a service.