Enable more tokens on the testnet chains

[theCastleBuidler]

Describe the solution you'd like It would be good if you can enable more tokens on the testnet chains, and also have the mint functions open in the new contracts. I think it would be very helpful for scenarios and apps where multiple tokens are needed and the app is not production ready yet. I am specifically asking this because I need multiple tokens for my Scaling Ethereum hackathon app.