Disable update filter button when no values are selected
Disable update filter button when no values are selected

Fixes #523

Signed-off-by: Ryan O'Hara <0445eebf183a844044c8b11415ecf3b6065c7f75@email.chop.edu>

chop-dbhi/cilantro,chop-dbhi/cilantro,chop-dbhi/cilantro