Remove adding country code to tel number while dialing

Fixes #176

'tel:455' is dialed as 455

'tel:0800213456' is dialed as 0800213456

'tel:+380961234567' is dialed as +380961234567

'tel:+38(096)123-45 67' is dialed as +380961234567 (non-numeric characters will be removed, except '+')

'tel:123-456-789;phone-context=+48' is dialed as +48123456789

I've tested on my development machine.