updates for ExternalERC1155 contract + deployment

[x] get ownerOf function working again by altering _mintNft function and overriding safeTransferFrom function
[x] write a new deploy script H_ExternalERC1155.js to deploy ONLY the ExternalERC1155 contract
[x] deploy ExternalERC1155 on Kovan
[x] verify contract on Etherscan: https://kovan.etherscan.io/address/0x607De5Fb7740A480e721942a91312Aa9e5637B89
[x] manually test that ownerOf is working correctly using Etherscan
[ ] write tests for the ExternalERC1155.js contract to test programatically what happens with ownerOf on ownership changes
[ ] copy H_ExternalERC1155.js deployment script into 3_tokens.js script

Charged-Particles / charged-particles-universe