Allow only numbers

When writing to the hidden text field, users could insert any character if they are using a bluetooth keyboard (for example). This filters non-numeric characters.
Update ABPadLockScreenController.m

This fix will allow the screen to work with iPad applications that have the interface orientation set to Horizontal.
So we don't display the pin screen in a different orientation related to the iPad.
Merge pull request #6 from wolffan/patch-1

Update ABPadLockScreenController.m
Merge pull request #5 from EgoAleSum/patch-1

Allow only numbers
New iOS 7 version (code only) started
Updated appearance proxy on ABPadLockScreenView and ABPadButton
Pin indicators are now appearing
Added delete functionality
Basic unlock functionality
User can now be locked out after attempts expire
Slight tweak for attempts logic
Added attempts delegate methods
Made it look nicer
Abstracted duplicate logic from lock and setup screen into abstract class
Pin set functionality enabled
iPad layout now centred
Resolved final iPad rotation issues
Added support for iPhone 4
Added license
Updated example project
Added pod spec
Added git ignore file