add check to see if process is running
add check to see if process is running

because when we interrupt the tests via ^C, the signal also kills the
background process

OpenZeppelin/openzeppelin-contracts,OpenZeppelin/openzeppelin-contracts,dmx374/zeppelin-solidity,OpenZeppelin/zep-solidity,OpenZeppelin/zeppelin-solidity,OpenZeppelin/zep-solidity,pash7ka/zeppelin-solidity,pash7ka/zeppelin-solidity,OpenZeppelin/openzeppelin-contracts,OpenZeppelin/zeppelin-solidity,dmx374/zeppelin-solidity