improved phone number validation

Improved phone number validation based on google's libphonenumber.
Therefore I compiled their lib into one file (see [https://github.com/codedust/libphonenumber-api](codedust/libphonenumber-api)).

Also the users regionCode (eg. US for the USA or DE for Germany) is now stored. This makes it possible to enter a regional number (without '+' and country code) direktly into the textfield in the popup.
Cant this be derived just from the phone number?