Crypto: encrypt/decrypt, move cryptopp to implementation, tests.

Note: ECDH and ECDHE key exchange are still under development. I would like these schemes to be reviewed however encrypt/decrypt is primary focus; ECDH-related classes and tests will be removed along with ECKeyPair prior to merge.
Public is a fixed hash so I added static_assert. memcpy remains as it is the simplest way to perform this operation. Public is a FixedHash which is a fixed size, so I've used Public::size to bound copy operation. Same w/Secret.

Note that, Public will be resized to 33 and/or 65 bytes. Uncompressed keys represent two integers. One integer can be replaced with 1 or -1, which is enough information to recover it's value.