copying out existing versioned-serializers code into shared/serializers/, adding into available serializers, doing proper imports and references.
cleanup from debug session that I missed in initial self-code-review.
rename 'version' to 'minversion' for versioned syncing
Merge branch 'develop' of github.com:learningequality/ka-lite into save_the_django_serializers
cleaning cruft from django's serialize object
re-enabling fixture tests
Merge branch 'develop' of github.com:learningequality/ka-lite into rename_to_minversion

Conflicts:
	kalite/utils/general.py
Merge branch 'develop' of github.com:learningequality/ka-lite into redirect_to_force_sync
OMG a merge conflict in a docstring. LOL
new katest management command "clean_db"
Added tests for VideoLog and ExerciseLog saving, including 2 that fail.

Also, minor cleanup on imports on securesync tests. They still pass.
preventing central-server regret
adding empty string as default value for forms.
creating browser-based regression tests.  cleaning up form-based errors--one form used a non-standard / different error class.
__unicode__ function must use u'' format strings (see registration app for an example like these changes.
adding tests
making __unicode__ work on unsaved objects; gracefully failing sign() on unsaved objects
unicode tests for main objects
refactor confirm logic in katest clean_db
Merge branch 'develop' of github.com:learningequality/ka-lite into error_on_empty_form_fields