Brings better compatibility between "testnet" and "regtest". Services such as
Bitcore Wallet Service and wallets such as Copay that have "testnet" and not
"regtest" will be compatible with "regtest" if enabled in a Bitcore node. This
adds two new API methods to enable/disable regtest on the testnet network:
- `bitcore.Networks.enableRegtest()`
- `bitcore.Networks.disableRegtest()`