Added option to pass opts through to PourOver's makeFilter() functions, this lets you use a different filter name from the attribute being filtered.
Added the ability to pass something falsey as values to addFiler and have it use the attr set in opts.attr to fetch possibilities for the filter. Added test that values can be falsey and work as expected, added test that two filters using the same attribute can be used.
Merge pull request #6 from maxbrokman/master

Added option to pass opts through to PourOver's makeFilter() functions, ...