Disabled randomness and improved unit tests.

- Working on tracking down encryption/decryption bug. Pattern is consistent across blocks, but incorrect bytes are being read/written.

- Fixed a bug in addition that was preserving monomials that don't
  contribute.

- Implement polynomial function equals method and hashcode.
Fixed encryption / decryption and added envelope.

- Added Ciphertext envelop capable of supporting homomorphic string
  concatenation.

- Added support for arbitrary block length to zero padding strategy.

- Added static factory method for XOR function.

- Partially completed homomorphic xor.