Connect through HTTP Proxy

[heydavid525]

Thanks for the wonderful project. My setup is a bit unique: I'm setting up eth-proxy behind a firewall that can only allow connection through a http/https proxy. In other words, all my machines can only talk to the outside world through this proxy. I wonder if it's easy to support that? I can try to implement it given some pointer.

PS: I'm on Ubuntu 16.04

Thank you!