Deal with ambiguous Geocoding for other States

Proposed change to deal with ambiguous geocodings on a state-by-state basis. This change does 2 things:

1. Adds a new setting (state) in `ansible_vars.example.yml` that takes as a value a two letter state abbreviation (e.g. PA). This will then get written to the local_settings file, should make it easier to deploy as well.
2. `cicero_search.py` uses `settings.STATE_FILTER` to filter out ambigous addresses outside a given state.

Filter addresses on a state-by-state basis seems necessary since when
ambiguous addresses like '1234 Market St.' are entered the results may include
cities in states that the site does not serve.