Changed rsaSign() parameter name from 'message' to 'data' to avoid confusion
Changed rsaSign() Javadoc description.
Renamed encryptHybrid() to encryptHybridAndSign() and
decryptHybrid() to decryptHybridAndValidateSignature() because encryption
and signing are indepented operations. This should be expressed by the
method name.
Merge pull request #62 from L-Henke/cryptoImprovement

Changed rsaSign() parameter name from 'message' to 'data'
Catch org.bouncycastle.crypto.DataLengthException in rsaDecrypt()