execute post install tasks when called via `pip`
execute post install tasks when called via `pip`

closes #833
pip is odd, hopefully this won't cause side effects.
monaparty/counterparty-lib,CounterpartyXCP/counterparty-lib,CounterpartyXCP/counterparty-lib,monaparty/counterparty-lib,F483/counterparty-lib,F483/counterparty-lib