Sinatra Reloader in place

Once merged into master you shouldn't need to kill Sinatra and start it again when you modify a template or add a new end point, it should be picked up automatically.

I've added the appropriate Gemfile so we start doing things correctly as per Ruby-world. Make sure you run ```bundle``` on the root of the project after pulling so you get ```sinatra-contrib```.

@adamtaylo all yours.