chore(requirements): update pip requirements to latest stable.

Makes all the packages in requirements to it's latest. The following packages are updated:

django-configurations==0.5.1 # Latest 0.8
django-cache-url==0.6.0 # Latest 0.7.0
django-braces==1.2.2 # Latest 1.3.1
django-floppyforms==1.1 # Latest 1.1.1
South==0.8.2 # Latest 0.8.4
django-model-utils==1.5.0 # Latest 2.0
Pillow==2.1.0 # Latest 2.3.0
django-allauth==0.13.0 # Latest 0.15.0
psycopg2==2.5 # Latest 2.5.2
django-autoslug==1.7.1 # Latest 1.7.2
gunicorn==0.17.4 # Latest 18.0
django-storages==1.1.4 # Latest 1.1.8
gevent==0.13.8 # Latest 1.0
boto==2.9.5 # Latest 2.23.0
coverage==3.6 # Latest 3.7.1
django-discover-runner==0.4 # Latest 1.0