Fix the program overriding options with defaults

Author: alexcanessa

lib/src/Program.js

@@ -172,7 +172,7 @@ class Program {
         }
 
         return Object.keys(defaults).reduce((carry, option) => {
-            if (object[option]) {
+            if (object[option] && object[option] !== defaults[option]) {
                 carry[option] = object[option];
             }