Add Network Support for Ephemery Testnet

[gconnect]

There is currently no support for Ephemery using the --network=ephemery flag.
In addition to adding the genesis flag the Ephemery implementation also requires a genesis reset function.

For context, Ephemery Testnet was initiated by @taxmeifyoucan. Ephemery testnet is a network that rolls back to the genesis after a set period of time. It is focused on short term and heavy testing usecases. This is also to avoid problems like insufficient testnet funds, inactive validators, state bloat, and similar issues faced by long-running testnets.

[macfarla]

closed by #7563