Fix/position

The octokit api expects position, not line number, which is what you are giving it, however this keeps it all named the same.

I also updated the readme with a step I needed to get it running locally.

This all passes except [this test](https://github.com/thoughtbot/hound/issues/311) which failed on a clean slate.
@gylaz how about this attempt?

I use to think you could put multiple rake command on a single line `rake db:setup db:test:prepare` but it never executed the prepare task, so I moved it to it's own line.