Rename CourseLocator.revision to branch

Fix some pylint issues

Make render_template mocking clearer

fix for ie bug where drop down menus were still clickable when collapsed

Cale/lms xblock student view

Fix broken Studio signup.feature acceptance test

Fix word cloud modules not exporting correctly.

Jonahstanley/upgrade chrome version

Quiet mongoimport noise during tests

Remove get_preview_module.

"Graphical Slider Tool" integration into studio

which a previous refactoring had replaced. Coverage of locator.py is
100%

This makes the LMS use an XBlock's student_view, rather than an
XModule's get_html to render for display. However, it does not yet use
wrap_child to handle instructor debug information or url rewriting.

[LMS-219]

`world.css_find()` to protect against StaleElementException
in Jenkins.

make user api work with basic auth

    And replace calls with calls to load_preview_module.

E0d/fix feature flag

Grant admin rights to members of the course team

and all related vars and methods.

This allows a more general approach to modules such as word_cloud and
video which have no XML data (it's all store in metadata), but use
XmlDescriptor for backwards compatibility. They now generate an empty
tag on export, and clear out empty tags on import.

Also a small change to the video module as a result -- if it's asked
to parse empty XML data, it won't try to parse anything.

Yet another Course Info bug