Add gist.el

[lwiechec]

Would be easier to share things around with gist.

[lwiechec]

installed gist.el only to discover that it does not work from behind the HTTP proxy (at least - not straight out-of-the-box).

Notified the author of gist.el about that by raising an issue on this project. We'll see what comes next :)

[lwiechec]

Got reply from the author:

think the right way to achieve that would be to configure url-proxy-services according to your environment. Now, I'm not able to test that at the moment...