Added signature to encrypted messages.
Changed visibilities of methods in CryptoUtils.
Added log messages for (currently) unhandled exceptions.
Fixed usage of wrong RSAPrivateKey in CryptoUtils rsaSign()
Fixed sub-key signing. Changed method named in CryptoUtils
Fixed CryptoUtils rsa sign fix again
Changed CryptoUtils logger to final static
Merge pull request #59 from L-Henke/cryptoImprovement

Added signature to encrypted messages and CryptoUtils improvement.