Add fuubar as formatting option

[tomasdundacek]

Hi @briandunn

Thanks for this brilliant gem! After reading the discussion in #87, I've been working on an option to allow other formatters to be used with this gem.

I have re-added the -f CLI option, and eventually I would like to - in a different PR - create an option to have a .flatware file to store these options in the repo.

Closes #87

[briandunn]

I am interested in merging the addition of more notification types, and the formatter const lookup. Could the actual fubar adapter be a separate gem though, like flatware-rspec-fubar or something, and adding that to your project Gemfile would enable it's use? That would be more like the patterns of rspec, and would open the door to further cool formatters without adding more maintenance to this repo.

[tomasdundacek]

@briandunn Thanks for the feedback, and yes - splitting the gem makes sense. I'm a little busy currently, but I will have a look at it in near future.