Added missing :target: to travis-ci target
- Added info regarding python3 support
Updated installation instructions because this branch will not exists on a pip mirror.
- Added info about hiredis support for this branch to Readme
- Updated maintainer name and email in setup.py
- Minor updates to Readme
- Minor cleanup in tests
- Updated all .py files to have the same header
 - Removed unused imports
 - Updated all impotrs to not use relative package imports