Better invalid location handling

[nickoneill]

Currently if you arrive at an issue page with an invalid location (i.e. outside of the US, or somewhere that google civic can't determine any reps) the page is blank because of the thrown invalid address error.

If I comment out the thrown error, the call appears without a contact but with the outcome buttons.

We should message an invalid address in the location selector, but also in the call details. And remove the outcome buttons since they don't correspond to a contact.

[cdoremus]

The outcome buttons are removed in PR #64 if there are no contacts affiliated with an issue.

[cdoremus]

PR #64 seems to have fixed this issue (not just the outcome buttons), but we're waiting for verification from the person who reported it.