Ask for framework and template in interactive mode

[PaulRBerg]

Create Eth App is powerful - it lets you choose-your-own-adventure via the --framework and --template CLI arguments. However, these options are not allowed when running Create Eth App with no arguments, i.e. yarn create eth-app or create-eth-app. Should we ask the user about them?

This is meant to be a discussion, since I'm not yet sure if the payoff is worth it.

[TomAFrench]

This would help with discoverability of different templates if we showed a menu of possible options.