Implemented encryption and decryption via ECIES.

Probably used wrong parameters for the operations, need to work out what
PyBitmessage uses.
Created POW Performance Test cases
Started to implement the encryption
Doing some testing about the encryption format.
Implemented decryption, fixed wrong key in encryption.
Made en- and decryption work
Merge pull request #8 from ISibboI/Sibbo

Sibbo