Django 1.5: used the receiver decorator

Mostly syntactic sugar to allow connecting various signals to the same
handler. Other signal handlers have been left intact.

Fixes evernote#176.

Conflicts:
	pootle/apps/pootle_project/models.py

Cherry-Picked-From: 97eea7338c36678f2eadd2656f239efeb4eada24
Requirements: use stable version of django-debug-toolbar

Per evernote@2660327
Cleanup: removed dead template filter
Cleanup: Use render() instead of render_to_response()
Cleanup: Get rid of __future__.absolute_import imports

Despite what the docs say, this is available from 2.6 onwards.
djblets: Use json instead of simplejson
Cleanup: Remove pootle_misc.redirect

All it does is what django.shortcuts.redirect does, with unused extras
Cleanup: Prefer redirect() over HttpResponseRedirect
captcha: Simplify the regex
util: Drop unused imports
translationproject/views: Make the import block more readable
Tests: Revert tests that break on mysql (sigh)
admin/util: Simplify process_modelformset() and avoid dual-instancing
README: Add a travis badge
tests: Swap the order of two tests
admin/util: Get rid of an unnecessary duplicate call
Cleanup: Remove unused import
Removing Languages from Django admin

The preferred way to alter languages is using our ADMIN. Also moved
the code to forms.py and did minor simplifications to form code.
Bugfix: Make delete action work again

Before this the link used in the delete action was not providing a
correct URL (without the language code at the begining) and thus the
action din't work.
Also update TP counts on unit deletion