added getCards functionality to Customer
added call to get bank accounts associated with customer uri
fixed documentation wording
fixed documentation string wording
changed Credits.add parameters to be similar to other functions. (allows other fields to be passed as json body data)
fixed function documentation
updated tests to new Credits.add syntax
added backwards compatibility to Credits.add changes
added test for getBankAccounts
added test for getCards function
finishing up final issues with reversals and completing tests and adding reversal scenarios
Merge remote-tracking branch 'StephenCWan/feature/customer_getcards'
Merge remote-tracking branch 'StephenCWan/feature/customer_getbankaccounts'
Merge remote-tracking branch 'StephenCWan/feature/credits_add'
fixing change to Credits.add