- social auth added
- github backend enabled (for tests mainly)

NOTE: to use it properly in test environment you should:
1. Go to https://github.com/settings/applications/new and create new application:
     Application Name: <any-name-u-like>
     Main URL: http://localhost:8000/
     Callback URL: http://localhost:8000/
2. $ export GITHUB_APP_ID=<ur-github-app-client-id>
   $ export GITHUB_APP_SECRET=<ur-github-app-client-secret>
   $ python spear/manage.py runserver