Workaround for pin focus (bug 956959)

This is a hacky workaround for the pin focus issue on android + b2g 1.3. [1] 

Before adding the timeout I tried to backport large chunks of the Spartacus JS which doesn't have the same problem and didn't succeed in fixing the problem.

As the webpay UI will all be replaced by Spartacus in the not too distant future I think this hack is a reasonable stop-gap measure. 

Whilst in this code I also:

* Added a pin view purely for testing purposes to make it easier to work on.
* Fixed the x-inputmode attribute which was incorrectly pluralized (something I discovered working on Spartacus)  - This means that where supported the keyboard will only show digits and not additional chars (e.g. periods etc).

[1] https://bugzilla.mozilla.org/show_bug.cgi?id=956959