CryptoPP ecdh and ecies

Tests for primitive crypto w/cryptopp and concept for peer auth. These tests will be moved to test/cryptopp.cpp as dev::crypto develops.

Not tested:
* pbkdf2
* peer-trust handshake (New, Know, Unknown, Blacklisted)
* genesis wallet
* (1) ECDHE-ECDSA-WITH-AES-128-CBC
* cryptopp ECDSA vs secp256k1
* cryptopp sha3 vs eth sha3 (even to assert incompatibility)

(1) I need to look at what TLS uses PRF for. PRF seems to be overkill when we expect peers to have persistent keys, it's a trustless p2p protocol, and whisper will be used for authenticated (trusted) communication.