Specify error type in manual_testvectors file

[rllola]

In order to improve testing we should add error type for invalid transaction.

Example :

    {
        "description": "Address protocol 2 Invalid payload length of 21 bytes",
        "encoded_tx": "iFYCAAAAAAAAAAAAAAAAAAAAAAAAAAAAVgIAAAAAAAAAAAAAAAAAAAAAAAAAAAABRAABhqBDAAnEQwBhqABA",
        "valid": false,
        "testnet": false,
        "message": {
            "to": "f2aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa3sien4",
            "from": "f2aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa3sien4",
            "nonce": 1,
            "value": "100000",
            "gas_price": "2500",
            "gas_limit": "25000",
            "method": 0
        },
        "encoded_tx_hex": "88560200000000000000000000000000000000000000000056020000000000000000000000000000000000000000000144000186a0430009c4430061a80040",
   "error": "Invalid payload"
    }

Error should probably be a regexp.

:link: zboto Link