Reorganize files to match other OmniAuth gems

I moved files around and changed the gemspec to match how other OmniAuth gems do it.  I also changed some of the info keys to be symbols and removed UID from info since it is already part of the info returned.  It is grabbed in the `uid` method.  Lastly, I added a `.gitignore` and removed the `Gemfile.lock` since it shouldn't be in the repo.