Test better

- Splits two stages of `spatialmatch` into `spatialmatch` and `verifymatch`
- Adds an `options.limit_verify` to `geocode()` primarily for testing
- Extends memsource to actually make it capable of use for full geocoding tests
- Adds isolated self-contained geocoding testcases that don't rely on existing indexes or fixtures

- [x] Shouldn't alter the behavior of carmen from `master` but worth a testing runthrough anyway.

cc @ingalls @morganherlocker