Create User Accounts and allow for interaction with msg.sender and accounts stored in ADDRESS data types.

In #30 we create the data type, but in this issue we need to support setting the msg.sender before calling a function, support address.transfer(AMOUNT) (the smart contract is sending money to address, for the AMOUNT of ether - positive decimal)

Allow the user running our program to give all account names (need special comment command for this)

Related Issues: #30