get_accounts():  Change task from getAccountsSortedByBalancedDescending to getAccountsSorted
api.py:  Turned into a class
Mint class:  Added proper factory method create(); made email and password optional to get_accounts()
Mint class:  + folding
Mint class:  + populate_extended_account_detail() and supporting functions.  This retrieves the stuff that would be displayed on an account's detail page - total fees, available/total credit, etc
Mint class:  + get_budgets() and supporting functions