Also contains:
* mattdrayer/rebase-20140722b: cherry-pick 0325694
* mattdrayer/rebase-20140722: cherry-pick e8b1217
* Sessions API Documentation
* mattdrayer/rebase-20140722: cherry-pick ofao48d
* mattdrayer/rebase-20140722: cherry-pick b0c343c
* mattdrayer/rebase-20140722: cherry-pick d56e973
* mattdrayer/status-500-fix: Small API bug
* added content_id to workgroup review submissions
* mattdrayer/api-user-preferences-delete: Added new Detail view, GET/DELETE operations
* mattdrayer/rebase-20140722: cherry-pick 0624385
* handle exception if user never accessed any course module
* mattdrayer/rebase-20140722: cherry-pick caada51
* cdodge/add-progress-publish-api-endpoint: expose a new xblock runtime publish special cased event type 'progress' which adds an entry into the CourseCompletions table
* add default setting for feature flag in common.py
* mattdrayer/rebase-20140722: cherry-pick 7a1e12c
* mattdrayer/rebase-20140722: Functional stabilization
