CB-6563 - Keyboard: Fix issue with UIPickerViews breaking.
(closes #11)

Going from a keyboard to a select dropdown picker triggered the show
handler without ever calling the hide handler. Going from a select list
to a keyboard triggered show again. At this point, the UIWebView had
been shrunk to the point of having a height of 0.

Signed-off-by: Shazron Abdullah <shazron@apache.org>