added a default constructor for colortransformation

Author: Paul Ruiz

IconColorization/app/src/main/java/com/ptrprograms/iconcolorization/utility/ColorTransformation.java

@@ -15,6 +15,10 @@ public class ColorTransformation implements Transformation {
 
     private int color = 0;
 
+    public ColorTransformation() {
+
+    }
+    
     public ColorTransformation( int color ) {
         setColor( color );
     }