Documents Geocoder.search method.

Except ZERO_RESULTS, which doesn't seem to merit a warning.

Wrong number of arguments for reverse geocode search.

Move to fetch_parsed_response. Will use search method for fetching a
Result object.

Also update contents of .gitignore from same.

This should have been part of commit 70cc64ee.

This allows the same model to be forward and reverse geocoded and still
provide a geocodable address though a non-attribute method. Also raise
an exception if sufficient configuration is not provided.

Move relevant methods into it.

Be more descriptive.

Move all network/lookup-related methods into it.