Allow for an empty string to be passed in to normalize_address when creating contracts
Allow for an empty string to be passed in to normalize_address when creating contracts

changwu-tw/pyethapp,gsalgado/pyethapp,ethereum/pyethapp,gsalgado/pyethapp,ethereum/pyethapp,RomanZacharia/pyethapp,changwu-tw/pyethapp,RomanZacharia/pyethapp