Date picker and typing fix for kif-next

- Interacting with views containing a UIDatePicker can cause KIF to hang because it will recurse down into a date picker's accessibility elements and get stuck there.

- enterTextIntoCurrentFirstResponder: no longer immediately fails if KIFTypist fails to find a key instead of falling back to entering the letter manually.
- enterText:intoViewWithAccessibilityLabel: wasn't waiting long enough for typing to finish on some slower machines. It'll now wait up to a second instead of failing after a tenth of a second.

CLA has been signed.