Feature/victor/file per descriptor

* Move lazyproperty decorator into xmodule so it's accessible during tests
* add default xqueue to test system

* test enrolls in course before testing pages
* support github edit links with new file structure
* Some pep8 cleanups

* means we get the same url_name on each import of the same data.

- add 'type' and 'points' to capa_module metadata
- replace old 'title' tag with display_name

TODO:
* need unique slugs for errors so they don't overwrite each other on export.
  - try to preserve origin slug.  If not possible, generate random one.

* figure out what metadata to strip.  e.g.
 ({'data': '<problem><p><h1>Finger Exercise 1...'},
    {'data': '<problem points="1" type="lecture"><p><h1>Finger Exercise 1...'},
    False)
  - where did points and type come from?  Do we want them there?


* separate broken and non-broken test courses

* course.xml is special--has org and course attributes in addition to url_name
* strip data_dir from metadata on export
* more asserts
* work on roundtrip import-export test

* +improve test.

* needed for CMS performance (can now save just an item, not whole tree)
* remove split_to_file methods
* simplified AttrMap logic
* write each descriptor to a separate file
* detect format on import and adjust appropriately.
* update tests

Kimth/lms coderesponse

Removing the <text> wrapper around choice text for radiogroup and checkboxgroup

fix typo in registration button jquery

make the staff debug information appear in a show/hide span

Fast grading

arjun/grading fix

Poor fix for a breaking change in which student answers that were arrays (e.g. those resulting from a checkbox group) would be converted to strings and graded incorrectly.

Fixed incorrect default argument so that tests run; however the new value is incorrect and needs to be fixed.

Don't contact queueing server on Django load

Edit link fix

merging this now because the it looks ok, and it fixes some bugs introduced by the last xserver merge, which are preventing the LMS from running in the current version of master.