Issue 3

This is a fix for issue #3. I did two quick tests. One with [a repository that did not have a hyphen](https://github.com/deanmalmgren/pr-test) and the issue2pr worked fine. When [a hyphen was added to the repository name](https://github.com/deanmalmgren/pr-test) though, issue2pr did not work :(. This has to do with the regexp that is used to extract the username, project name, and issue number in the regular expression. 

I'm not terribly familiar with sinatra so I'm not sure that my syntax is correct here. If I've bungled anything, let me know and I can add a quick patch.