Changed bit constants to byte constants
Renamed SYMM_ALT_TRANSFORMATION to SYMM_GCM_TRANSFORMATION
Throw InvalidKeyException instead of catch
Added and improved logging for catched exceptions
Removed unneeded re-initializations of gcmCipher
Added Javadoc about possible null return values
Added file/stream based en-/decrypt methods w/ tests
Merge pull request #218 from thechauffeur/roeslpa-thechauffeur-fileStream
Implemented multi sub-key support

Old getter are marked as deprecated. They will be removed when all other
methods have been changed to the newly returned Lists.
Merge pull request #207 from L-Henke/multiSubKey

Implemented multi sub-key support