Send a signed response with WS register

[zsoltpardi]

The app must send a signed message to the UI peer in the response of register
https://github.com/streembit/streembit-cli/blob/develop/transport/ws/handler_srvc.js#L150

The payload apart from the token which included already must include this data:

{
"token": "abcd",
"data": {
"pkhash": "xyz",
"time": 12345
}
"sign": "abcdefgh",
"public_key": "the application public key"
}

• pkhash: UI client pkhash
• time: time of signature
• sign: CLI PKI signature of the data field
• the main ECC public key of the app