Added Account.find method
Added Account.find method

Could later be extended to find addresses by their first few characters.

changwu-tw/pyethapp,kustomzone/pyethapp,d-das/pyethapp,RomanZacharia/pyethapp,ethereum/pyethapp,vaporry/pyethapp,gsalgado/pyethapp,ethereum/pyethapp,RomanZacharia/pyethapp,gsalgado/pyethapp,changwu-tw/pyethapp