Correctly handle 404 exceptions for static files during development.
Store thumbnails in individual directories named after the original filename, so that we can accurately delete them from within filebrowser where necessary. Closes #995.
Update thumbnail test path.
Added sanidentalgroup.com to sites in README
Disable the 'Add' option of comments in the admin, because the program crash when you try to create a new comment, is better delete this option for avoid this problem.
Add a new site

Add new site created with Mezzanine
converted ratios to floats

ratios were integer division, which didn't work as desired. casting the numerators to floats cures this ailment
added padding color option into thumbnail tag
More thumbnail tweaks - don't prefix image's thumbnail subdirectory and comment the reasoning for the sub-directory, use hex strings for color and include in thumb name, and pep8 fixes.
Document optional thumbnail tag args
Minor fixes for building docs.
Added pythonbc.co to sites in README
Fix thumbnail test
pep8 fix
Added USE_L10N check for language dropdowns in admin.
Added mezzanine-agenda to third party apps list in README.
Merge
Fix USE_L10N check for admin language selector.
Handle null descriptions ofr settings in conf form.
Added www.theartrebellion.com to sites in README.