Locations for everyone

This exposes locations as a separate thing from CommTrack. Actual locations are still really only useful if you have CommTrack turned on, but this is step one of getting Sheels monster feature out.
Background of this method: I was frustrated that I keep having to do a lot of the same things for these migration management commands, so tried writing some generic method to make use of. I didn't really find it any easier so didn't reuse this elsewhere.

I used both because I wasn't positive on how to go from having...

```
foo = CommtrackConfig.get_db().view(
    'commtrack/domain_config',
    reduce=False
)
```
..and then getting just `CommtrackConfig` back out.