Verify raw tx format when send raw transaction

[classicalliu]

Will reject tx with invalid RLP format

{
    "jsonrpc": "2.0",
    "id": 2,
    "error": {
        "code": -32602,
        "message": "invalid argument 0: rlp: non-canonical integer (leading zero bytes) for s, receive: 0x0013d2f7290ba5aff8911b28871c8e6b624117a711dea4f1484e0dc9d587d60a"
    }
}