quick commit before license implementation testing.
Working license checker!
Changing input method to InputType.TYPE_CLASS_PHONE to address one issue
in #37.
Updating with correct developer email string
Updated strings.xml with new strings for block addition dialogs.
Added strings for add/delete dialog to avoid using hard-coded strings.
Added libphonenumber library to make sure phone number is valid before
allowing input.

Uses to device's locale to efficiently determine valid numbers on a
country by country basis.

Fixes #37.