Add ability to create phone intents

It would be convenient to be able to make phone calls/dial numbers.

Example API:

``` java
Shelly.phone()
    .number("1234 123 123")
    .dial()
```

``` java
Shelly.phone()
    .number("1234 123 123")
    .call()
```

Where call would call the provided number, and dial would dial the number but not the call.
