Permission check on user object rather than username - fixes #1178
Updated django to 1.5.4
pick latest packages if available
remove rest framework swagger app, not in use
add django-taggit app
add tags to xforms and submission instances
Merge pull request #1242 from modilabs/django_1_5_4

Updated django to 1.5.4
api support for tags
updated docs for query and tags
add $all to mongodb whitelist
add TagListSerializer
tag forms
tag data submissions
update docs
update docs
do not generate url link if obj is None
turn tag list into a string representation
refactor bookmarks to labels
test add, remove, form tags
update util function to set api permissions for users