Added SMS messaging interface

SMS request logic is now a part of the `DialerFactory`, and can be invoked anywhere, just like calling logic (even using the same parameters). The `DialerFactory.sms` method creates an Ionic popup prompting the user to type in a message, which is then passed into the server request.

Basically, wherever `DialerFactory` is injected, a messaging popup can be invoked in the same way that a phone call is invoked.