Added ability to use full GitHub URL in search

[twolfson]

As initially proposed in #15, we want the ability to paste full GitHub URLs into the search box. This is to make it easier when searching for an application (e.g. instead of clicking/dragging exactly for the name, we can select the address bar in two clicks).

In this PR:

• Updated #search.submit Coffeescript to coerce https://github.com/org/repo to org/repo
  • For example, https://github.com/hstove/issue_stats -> hstove/issue_stats
• Fixes #15

Missing:

I wanted to write a test for this but I didn't see anything testing search form submission via git grep -i =/

[hstove]

Thanks! Sorry for just getting to this.

[twolfson]

Awesome, thanks for landing this =)