Numbers with space characters fail to dial. Support "tel:" url. Don't rely on model name.

Fix: Numbers with space characters fail to dial.

Fix: Don't assume openURL will always succeed if model='iPhone' and always fail otherwise.
 (e.g. future 'iPhone Simulator' may have a Phone app, or VoIP tel: support may be added to iPad.)

Add support for "tel:" url as well as raw phone number as param.