adding phpunit as a dev requirement
let travis use the required phpunit lib
update developing.md
adding a ParametrizedHasher
adding the ParametrizedHasher to the docs
Merge pull request #1 from kpacha/phpunit

Add the phpunit requirement in composer
Merge pull request #2 from kpacha/parametrized_hasher

Parametrized hasher
Add .idea to gitignore
- Minor PHPCS fixs on ParametrizedHasher
- Change a private method to protected at ParametrizedHasher
- Add a test to ParametrizedHasher