Merge pull request
#1670 from takluyver/pastebin-gist...
Merge pull request
#1670 from takluyver/pastebin-gist
Point %pastebin to gist.github.com.
Unfortunately
http://paste.pocoo.org has closed down. This updates the %pastebin magic to use gists instead, and adds a -d flag for the user to provide a gist description string.
We don't try to use any of the advanced features of gist, such as authenticating to make gists associated with your account. That could be added if there's demand for it, but for now we just send some content and return a URL.
