Made a lot of changes to the way we select a parser

- new yaml file
- added options to bin/upcoming_gigs.rb
- refactored lib/upcoming_gigs.rb to use the new yaml file format
- Adjusted the public bar parser into a different layout. It now only
  has a Parser class with methods for each parser in it. I've hastily
done this, so could refactor the layout here so each parser is in its
own file.