Support proxy server

[pdaugavietis]

Hi - trying to get this to support proxy servers, as it's a requirement for my implementation. I'm not seeing an easy way to pass thru options to HTTParty, but i think on HTTParty side should be easy to add the necessary options for proxy support if needed.

I'm wondering if maybe a bit of refactor around HOW options are passed back to HTTParty - maybe a hash instead of just a bunch of KV pairs? Thoughts? Help? :)

[pdaugavietis]

PR for this ended up doing a few more things - commented in PR thread.