Return structured function signature data with API responses.

[pipermerriam]

Currenty the data returned from the API looks like this.

{
  "id": 145,
  "text_signature": "transfer(address,uint256)",
  "hex_signature": "0xa9059cbb",
  "bytes_signature": "©\u0005�»"
}

I think it would be more universally useful if it looked like this.

{
  "id": 145,
  "text_signature": "transfer(address,uint256)",
  "hex_signature": "0xa9059cbb",
  "bytes_signature": "©\u0005�»",
  "function_name": "transfer",
  "function_inputs": [
    {
      "type": "address"
    },
    {
      "type": "uint256"
    }
  ]
}