fix paver theming on devstack (SERVICE_VARIANT support)

When running in devstack, you need to set the SERVICE_VARIANT so that
assets.py knows what environment file to use.  Recall that in devstack
we have all our settings in ../lms.env.json, not just ../env.json.  So
you need to run like this:

    SERVICE_VARIANT=lms paver lms --settings=devstack

Previously you'd get this error:

    Warning: could not find environment JSON file at 'lms.env.json'

Note there is no path on the file, that's the bug.  By making
self.REPO_ROOT absolute, we can walk up the tree and correctly find
the file, which is /edx/app/edxapp/lms.env.json fwiw.

Help paver find the theme directory

Documentation for changes to static pages

Paver v3

STUD-1347

Make emails in lms translatable

The email texts in lms/templates/emails are not extracted by rake i18n:generate because the babel_mako.cfg does not include them.
And a several emails are not translatable because they do not use ugettext.

Removing ipython from edx dependencies

Internationalized submission history view.

Ipython is not strictly required to run edx-platform. It can
be setup as part of Vagrant provision scripts, or manually
by each developer as required in specific cases.

Video: Fix flaky acceptance tests.

LMS-2167

Added template for iFrames. [BLD-611]

Fix Studio's XBlock dependency loading issues

STUD-1465

Changed the XBlock rendering logic to use promises to track asynchronous tasks.
Each dependency is then only loaded once the previous one has completed, and the
XBlock initialization only happens once all dependencies are loaded. This gives
XBlocks the same semantics in Studio as they get when shown directly on a page.

Display error page templates, for testing purposes

This commit allows us to test the server error template by visiting `/500`. This
way, we can catch errors in our error templates, instead of having infinitely
recursing errors.

Added ENABLE_MKTG_SITE to Features

Concept XBlock prototype

Test environment taking a little longer than expect. Jarv said okay to merge, so merging, 

and print errors and warnings to sys.stderr

Simpler and clearer

Update translations (autogenerated message)

Install new ORA (edx-tim)

Fix typo in studio's email text

Support for displaying submissions API scores in Progress page.

Clean up references to answer distribution-like things

The right parenthesis should be appeared before the method '.format', not after.

Remove duplicate code in transcripts_ajax.