Updated Django for 1.6.6 security release
update pillow 2.5.2 => 2.5.3

- A security release update for pillow.
Merge pull request #124 from theskumar/patch-2

update pillow 2.5.2 => 2.5.3
Update requirements
remove south
update django to 1.7
change migrations from south to new django format
fix sites migrations
Update README
Merge pull request #128 from talpor/master

Yay! Update django to 1.7 :+1: :+1: :+1: :+1: :+1:
Adding @alb3rto to contributors since he gave us support for 1.7!!
Update README.rst
fix(security/dj-secure): add missing middleware of django-secure

- For the working of django-secure the middleware class needs
to be added. (http://django-secure.readthedocs.org/en/latest/index.html#usage)
- add correct values for SECURE_PROXY_SSL_HEADER for heroku
Update CONTRIBUTORS.txt
Merge pull request #130 from theskumar/fix-dj-secure

fix(security/dj-secure): add missing middleware of django-secure
chore(): update links.
reverted pylibmc to 1.2.3 version

Reverted pylibmc to 1.2.3 version because django-heroku-memcacheify==0.5 require pylibmc==1.2.3 

https://github.com/rdegges/django-heroku-memcacheify/blob/master/setup.py#L18
Merge pull request #131 from luzfcb/patch-5

reverted pylibmc to 1.2.3 version
Added pytz to requirements/base.txt

Added the latest version of pytz (2014.7) to requirements/base.txt to
avoid errors with DateTime fields.
Added database credentials and security check for db password.

Added database credentials (user name: 'django', password: 'blank') and
security check for db password. The security check will raise an error
if the database password is 'blank' in production.