Remove (start,end)Address in favor of (start,end)Location.

There is no need to geocode an address first, the DirectionsService will do that automatically.
This saves 2 Geocoder calls and the overhead of loading the module.
Rename (start,end)Location to (start,end)Address.

Users of this should no longer notice any difference.
Merge pull request #14 from bamnet/master

Stop geocoding (start,end) address before finding directions.