Added scrypt license
Removed NULL block and steam ciphers to avoid mistakes
Renamed KeyFactory as KeyDerivator to be coherent with the future AsymmetricKeyGenerator
AsymmetricKeyGenerator and refactoring of public and private keys to create an API class to hold them
Implementation of ECKeyGenerator and refactoring of ECC stuff

closes #36
Moved block ciphers to a separate folder
Moved stream ciphers to a separate package
Removed TODOs and cleaned code
Prepare for 0.5.0 release
Changed docs tool path to new computer