Internationalize the forums post Markdown editor

This includes removing the "PREVIEW" label for the preview pane from CSS
and adding it to the generated DOM.
Reorganize documentation files for i18n

STUD-1094
Add function to generate documentation links

STUD-1090
Specific django-toolbar version (stable released) and update the panels in dev envs
Added myself in AUTHORS
Merge pull request #2177 from ovnicraft/django-toolbar-update

Django toolbar update
Merge pull request #2172 from edx/db/doc-build-url

Reorganize doc for i18n
Factor the core Capa problem logic into a mixin.
This mixin can be used by either the current XModule, or by an XBlock. Leave
the XModule-specific code in capa_module and move the shared code to capa_base.
Plan to move caba_base into the capa package in the future.
Merge pull request #2124 from edx/jorr/feature/factor-shared-capa-features-into-mixin

Factor the core Capa problem logic into a mixin.
Merge pull request #2201 from edx/gprice/markdown-editor-i18n

Internationalize the forums post Markdown editor
Detached categories don't access control on date
Merge pull request #2206 from edx/db/lms_date_agnostic

Db/lms date agnostic
Merge pull request #2207 from edx/release

Hotfix 2014-01-16
Merge branch 'master' of https://github.com/edx/edx-platform