Pyconfita

- Updated value processing: empty string should not be dumped. Only dump None values.
- Updated README

[Missed CHANGELOG update]

- Added case sensitivity option in Confita

- Updated setup.py and tools

- Initialized package
- Added Vault backend
- Added File backend (YAML format)
- Added Dict backend
- Added Environment backend
- Added explicit type conversion support (str, bool, int, float)