Added OSM geocoding

I had this project where we needed to run 100K rows... and kept hitting google's threshold (nor was able to get appropriate funding to allow for an API upgrade ;))...

So.. In a nut-shell: gives the user the option of google or osm (mapquest) as the geocoder. I looked around and didn't find anyone who forked your work to do this... or if there was anything ready-made. Your project is 2+yrs old. It can't be the only one, can it?? 

If you have the time, I'd love feedback on my code.. I seem to have a bunch of checks for the provider (osm vs google), but wasn't sure what the 'GO' way to code this would look like.