Add compatibility for new getData([]) with backward comp. of getData()

[Hugoo]

Latest version of the standard uses a new signature for getData([]), the lib should work with this new signature and be backward compatible with contracts using the previous signature of getData()

• Old ERC725Y interfaceId: 0x2bd57b73

{
      "stateMutability": "view",
      "type": "function",
        "outputs": [
          {
            "type": "bytes",
            "name": "_value",
            "internalType": "bytes"
          },
        ],
        "name": "getData",
        "inputs": [
          {
            "type": "bytes32",
            "name": "_key",
            "internalType": "bytes32"
          },
        ]
 }

• New ERC725Y interfaceId: 0x5a988c0f

{
      "stateMutability": "view",
      "type": "function",
      "inputs": [
        {
          "internalType": "bytes32[]",
          "name": "_keys",
          "type": "bytes32[]"
        }
      ],
      "name": "getData",
      "outputs": [
        {
          "internalType": "bytes[]",
          "name": "values",
          "type": "bytes[]"
        }
      ]
 }

the way to detect them is to use upcontract.methods.supportsInterface('0x37e619de').call() > true

[frozeman]

important for the erc725cache and UP website.