Feature/encryption


- adds symmetric encryption (AES) to peer communication, using the other's peer public key as passphrase.
- this prevents 3rd party eye dropping attack during wallet creation

This will be modified to asymmetric EC encryption once https://github.com/bitpay/bitcore/issues/287  gets implemented on bitcore. By doing this, 1-to-1 p2p communications will be protected from other peers in the wallet, also.