Removed _real_manager and _fallback_manager indirections as they were confusing and served no real purpose.
Made all 3 querysets used by TranslationManager customizable (translated, untranslated, default)
Reworked TranslationQueryset so its constructor takes the standard arguments again.
Add tests for FallbackQueryset
Allow passing None as one of the fallbacks - None will be replaced with current language at query time.
Change fallbacksqueryset to use a self join instead of multiple queries on Django 1.6+
Merge pull request #173 from KristianOellegaard/feature/fallback_refactor

Manager and Fallback cleanup, with fallback query refactor for Django 1.6+.