adds live server ports and hostname to app fig config
adds firefox repo to use latest firefox
use latest version of selenium, no need to specify version
Reworked the media-related template variables

Added a template context processor to the staticmedia app.  Use that
one instead of the one in utils.context_processors.  The
context processor sets up the STATIC_URL and MEDIA_URL variables.

Ditched COMPRESS_MEDIA, I don't think we really care about that one
anymore.  Ditched STATIC_URL_BASE.  I don't think we need second
variable when we already have STATIC_URL.

Removed a couple unused templates: videos/_offsite_widget.html and
embedder.html.

Updated other templates to not use COMPRESS_MEDIA or STATIC_URL_BASE.
Added support for storing static media on S3.

Added new send_to_s3 management command.  This basically does the work
of both the old compile_media and send_to_s3 commands.  Removed the old
unisubs_compressor commands.

Added method to calculate the git commit id and use that as our static
media subdirectory.

Implented static_url() when settings.STATIC_MEDIA_USES_S3 is True.