Fix offline_gradecalc

Bug: Throws error when can't find a user on the request object for grading or can't find a session attribute.

Fix: Added a user attribute with a value of the current student and a session attribute with a value of an empty dictionary.
fix crash in peer eval xmodule

As documented in Jira LMS-806:

Steps to reproduce:
* as one user, for a peer evaluated problem, enter something that needs
  peer grading
* as another user, log in and fire up the peer grading panel. You should
  see something that needs attention, a yellow exclamation badge
* clicking on the "do grading" panel will fail with a 500, stacktrace
  attached.
* it's possible that the question where this is being done must first have
  professor calibration done in order for peers to be able to actually get
  work to grade.

Don Mitchell debugged this with me and saw some problems in the ways
that the peer_evaluation xmodule code was accessing dates. Instead of
using the normal lms accessors, by going straight into the _module_data
it would be bypassing some important code (caching?). Fixing this to be
more standard did the trick.
Update Babel and Transifex libraries
Make descriptorsystem inherit from Runtime
Switch to studio_view
Fix repeated doc builds
Make builds quiet by default
redirects edge landing page to /dashboard
add a metadata cache and re-compute ignore when deleting a course to speed up the whole thing as well as squelching warnings in the console output
add same optimizations to the clone course command
rename clone.py to a more descriptive clone_course.py
Add TabsEditingDescriptor for VideoAlpha

Updates comment
Make Model descriptor class property.
Fix tests
Fixes
Fixed typo of function call. Added comment why it is necessary.
Merge pull request #571 from edx/valera/one_speed_html5_fix

Fixed typo of function call. Added comment why it is necessary.
Hotfix world cloud functionality
Merge pull request #572 from edx/vaxxxa/master-word-cloud-hotfix

Hotfix world cloud functionality
Refactor wrap_xmodule call
more template fixes for faq, press, and help
Merge pull request #565 from edx/adam/i18n-bug-fixes

more template fixes for faq, press, and help