feat(dimmer): opacity setting created invalid value on rgb background

When a dimmer already had a rgb background color, the opacity setting for the dimmer was not working because it created an invalid background color value .

Reason was because for a pure rgb value the third splitted string array element still had a closing parenthesis, which in turn created an invalid value like

rgba(111,111,111),0.1)

src/definitions/modules/dimmer.js

@@ -408,11 +408,11 @@ $.fn.dimmer = function(parameters) {
             var
               color      = $dimmer.css('background-color'),
               colorArray = color.split(','),
-              isRGB      = (colorArray && colorArray.length == 3),
-              isRGBA     = (colorArray && colorArray.length == 4)
+              isRGB      = (colorArray && colorArray.length >= 3)
             ;
             opacity    = settings.opacity === 0 ? 0 : settings.opacity || opacity;
-            if(isRGB || isRGBA) {
+            if(isRGB) {
+              colorArray[2] = colorArray[2].replace(')','');
               colorArray[3] = opacity + ')';
               color         = colorArray.join(',');
             }