Using proxy

[conilas]

Hey there!

I tried to use spotify-tui (which apparently uses this library) inside my company, where everything runs behind a proxy. After a little digging, I noticed they were trying to get the json token for oauth (https://github.com/ramsayleung/rspotify/blob/master/src/spotify/oauth2.rs), but the client from reqwest is being built without the proxy.

They have a good doc on it (https://docs.rs/reqwest/0.7.0/reqwest/struct.Proxy.html), so I was able to change the Client building line the proxy.

Question is: do you guys plan to have any take on that? I might be able to make a PR if that is not/not supposed to be in the roadmap or anything.

Thanks!

[ramsayleung]

PR is certainly welcome, It frustrated that I don't have time to add proxy feature to rspotify now, hence it's great if you could contribute to it.

[ramsayleung]

I have updated reqwest to the latest version, now rspotify supports system proxy by default(Notes that reqwest system proxy doesn't support socks proxy for now, check this issue for more details). For more details, please check this PR #70.