Adding context to Geocoder interface

[friend0]

Would you accpet a PR, or consider modifying this module such that users could pass a context to the Geocoder interface?
This addition would make this module much more powerful in production, since web servers would be able to pass the top level context for things like tracing and etc. The new interface would not be backwards compatible, but would be trivial for users to update, i.e. provide context.TODO to their calls as you've done

[codingsince1985]

hi @friend0, sounds like a great PR idea.