Proposed change to deal with ambiguous codings on a state-by-state
basis. This change does 2 things:
    1. Adds a new setting (STATE_FILTER) in settings.py that takes as a value
    a two letter state abbreviation (e.g. PA)
    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.
Probably a better idea to make this a setting in ansible_vars.yml rather than hardcoding and relying a change. Will also be able to use this for automated deploying different states possibly.
Merge pull request #14 from staterepme/geocode_filter

Deal with ambiguous Geocoding for other States