Add threaded comments to requirements

In django 1.6 the comment contrib library has been removed so we're
including that here as well.
Add commenting backend

Fixes #377
Merge pull request #880 from ahinz/fix/377/add-comments-for-real

Fix/377/add comments for real
Show comment form to logged in users
Merge pull request #885 from ahinz/fix/comment-form

Show comment form to logged in users
Firefox fix for streetview
Fix search_tree_benefits query to include plots outside an itree region

Also refactors converting tree(s) into a list of dictionaries, which is now
done by a helper function, instead of multiple places
Merge pull request #891 from maurizi/fix/ecoBenefitsDefaultRegion

Fix search_tree_benefits query to include plots outside an itree region
Add animated class to edit mode plot markers, fixes #741
Merge pull request #892 from maurizi/moveMarkerMessage

Add animated class to edit mode plot markers, fixes #741
Minor JS refactoring
Pulls date formatting into fieldHelpers.js
Reorders functions in inlineEditForm.js
Add proper date support to form_extras tags and inlineEditForm.js
Fixes #886
Use field.choices in form_extra.py to create dropdowns for fields
Loosen up identifier regex, allowing variables not named after models

Whitelisting the model part of model.field was a bit of a misnomer, since
it whitelisted the template variable name, not the actual model class it
represented.

Identifiers still need to be of the form "model.field" though, in order to
access the field metadata on the model class
Merge pull request #894 from maurizi/inlineEditChanges

Inline edit changes
Remove the animated class from the plot marker on first move
Add message informing users they need to move the marker when adding a tree
Fixes #741
Use django-extensions in DEBUG mode
Merge pull request #899 from maurizi/moveTreeText

Show move tree text