Update MiGS test with new credit card expiries

MiGS test credit cards (used in the remote tests) expire at the end of May 2013 (this month).

This commit simply updates to the new expiry year of 2017.

I have run the tests and 1 remote test fails (but that test did fail before the change).

I will try to address that failure (given I originally wrote the test) in a separate pull request.