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.
resolve merge conflicts
add escaping
one more escaping
add some unit tests for the new fields
be sure to encode the display strings
fix rebase conflicts
Limit the rate of logins.
fix more rebase conflicts
template errors
adjusting fix for studio drop-down nav in IE9
Merge pull request #560 from edx/adam/i18n-bug-fixes

template errors
Merge pull request #554 from edx/diana/django-ratelimit

Limit the rate of logins
Merge pull request #562 from edx/fix/frances/studio-ie-menu-bug2

adjusting fix for studio drop-down nav in IE9
Update Babel and Transifex libraries
redirects edge landing page to /dashboard
touch-ups per review feedback
fix formatting error
wrong accessor