When entering CC info in STPView, backspace on date puts user in awkward state

[elropero]

Have experienced the following with a few users, using STPView (Stripe pod version 1.1.4):

1. Enter full, correct CC#
2. Enter one digit for month of date, then backspace
   ** Cursor is now behind the last character of the 16th digit
3. From here, you cannot get back to the date, which is presumably what you were trying to do.

Only way to get back to date that I've found is to either delete the 16th char of the CC then re-type it, or to stop editing (implemented by whatever containing view controller is hosting the STPView).

Proposed change: deleting all date chars leaves the cursor in the date input field, rather than backing up behind the 16th CC digit.

[elropero]

The right place for this issue is probably on PaymentKit. I linked back to the description in the comments here: stripe-archive/PaymentKit#39

[jflinter]

Thanks for moving the issue to the PaymentKit repo. I've actually just removed PaymentKit as a dependency of stripe-ios, so I'm closing this issue here.