File en-/decryption with Streams

This adds en-/decryption which can handle big files by using Streams.
Additionally a test file is added to test this function (only ~100 Bytes).
#150 is closed by this.
First #146 and #161 have to be merged, then I need to rebase^^
Just looked the logger APi myself and found out that you can write `logger.error("asd", e1)`, so with the original exception passed as second parameter, not simple string concatenation.