Add GeoLite2 support, both City and Country databases
Add tests and make them pass
Add description of how to use GeoLite2 for IP geocoding
Fixes OID warnings when using PostgreSQL

Postgres correctly identifies OIDs when BEARING and DISTANCE contain
numerical values. It fails to identify OID for a NULL type.

This patch explicitly sets an OID type for NULLs when running in
PostgreSQL environment.
adds null_value method for code reuse
Merge pull request #734 from jzelenkov/fix_postgres_oid_warnings

Fixes OID warnings when using PostgreSQL
Use faster ruby methods
Add support for pure Ruby access to MaxMind database through maxminddb gem
Merge pull request #735 from jastix/master

Use faster ruby methods

See: https://speakerdeck.com/sferik/writing-fast-ruby
README clarification.
Be clearer about :google_places_details usage.
Merge branch 'feature/geolite2_support' of github.com:ChristianHoj/geocoder into pr/732
Rename from :geolite2 to :geoip2.

GeoLite2 is a free version of a product called GeoIP2. Both use the same
format.
Remove "EXPERIMENTAL" from GeoLite2 API.
Clarify README.
Rename config setting from :maxminddb_gem to :lib.
Prepare for release of gem version 1.2.6.
Add Sidekiq worker example.
Add lookup fallback initial interface to Readme; doc driven design... this may change.
Add simple execution strategy; this will run the query when we just have a symbol for lookup name