Added capability of returning all specs within a directory

Currently if a directory or potential filename is given only the first spec that matches is returned.  This change would return all specs that match.

You could then run your tests like so:

    bundle exec teaspoon test/javascripts/integration

or if using Guard

````ruby
watch(%r{test/javascripts/.+_helper\.(js|coffee|js\.coffee)}) { 'test/javascripts' } 
````

Thanks for the awesome gem!