Add link shortening

[jayhoogle]

Closes #130

Uses the Cutt.ly API to generate a short link when the user hits Ctrl+S. If there's an issue generating the short link, the current URL is returned instead.

Checking with the Cutt.ly team to see if localhost can be added as an accepted origin as those URLs currently fail to convert to a short link, and also to see if URL generation can be limited to the origins localhost and app.klipse.tech.

[jayhoogle]

@viebel here's the PR for my implementation of a link shortener. If you'd prefer a system that doesn't require a key, there is also the is.gd API which would provide much the same functionality but with a little less code, but still no ability to convert localhost URLs to short links.

[jayhoogle]

@viebel I haven't heard from Cutt.ly so I've reverted to using is.gd so the code is cleaner and a little faster to run, too. Also means there are no API keys in the code. Let me know whether you're happy for this to merge.

[viebel]

@jayhoogle Sounds good. Will review it soon

[jayhoogle]

@viebel great, thanks!

[viebel]

@jayhoogle The link shortening feature only makes sense in the Klipse web app. Please submit a PR to Klipse app repo.

[jayhoogle]

Closing in favour of this.