Adding Account and AccountList

Changes to Account:
getStatus and getAccountType now return a corresponding integer. (0 -
Active, 1 - Suspended, 2- Closed)/(0 - patron, 1 - staff, 2 - manager)

Changes to AccountList:
Added getId(int id) - returns an account with a matching id.
Added getAccountTypeList(int accType) - returns a list of accounts that
match the parameter.
Added serializeAccountList() - serializes the AccountList when called.
Updated add/removeAccount - will auto serialize the AccountList when
called.