Fixed: Add celery and librabbitmq to requirements.txt

These packages are required for the EDDA's asynchronous preparation of files for
users to download. The system uses Celery, which uses RabbitMQ, because there's
no reason not to go all out.
Fixed: Corrected MEDIA_ROOT and STATIC_ROOT Directories in setttings.py

I miscalculated the number of ".."s. And thought better of hard-coding
the STATIC_ROOT like I did. This is better because it both allows and
requires running "collectstatic," so other django apps' static files
will be served properly too.
Merge branch 'master' of github.com:ELVIS-Project/elvis-site

Conflicts:
	elvis/elvis/settings.py