Block num gt latest fix

[nicholasjpaterno]

Resolves #108
This updates ganache to match geth and parity when block numbers exceed latest

The only conflict occurs in eth_getTransactionCount where I opted to match geth's behavior.

#parity
swirl eth_getTransactionCount 0x00a329c0648769a73afac7f9381e08fb43dbea72 0xfff
{"jsonrpc":"2.0","error":{"code":-32602,"message":"Unknown block number"},"id":120}

#GETH
swirl eth_getTransactionCount 0x00a329c0648769a73afac7f9381e08fb43dbea72 0xfff
{"jsonrpc":"2.0","id":120,"result":null}

[davidmurdoch]

👍👍 Siskel and Ebert would probably give this PR Two Thumbs Up™