Bug - You couldn't manually delete everything in the textbox

Author: ruhley

lib/scripts/directive.js

@@ -286,7 +286,7 @@
                             control[0].$setDirty();
                         }
                     } else {
-                        if (newValue === null) {
+                        if (newValue === null || newValue === '') {
                             $scope.hue = undefined;
                             $scope.saturation = undefined;
                             $scope.lightness = undefined;