Merge pull request #2 from gchandrasa/master

Add Django custom user support
runtests_custom_user.py should only run on Django 1.5+
Added .travis.yml.
Updated test instructions.
Updated README.
Merge pull request #3 from gchandrasa/master

Add CACHED_AUTH_PREPROCESSOR_FUNCTION
Merge branch 'master' of github.com:ui/django-cached_authentication_middleware
Bump version to 0.2.0.
Fixed code block styling in README.
Change invalidate_cache function