SyncProperty: new setter method, fix tabs

library/Director/Objects/SyncProperty.php

@@ -23,6 +23,12 @@ class SyncProperty extends DbObject
     	'merge_policy'		=> null
     );
 
+    public function setSource_column($value)
+    {
+        $this->source_expression = '$(' . $value . ')';
+        return $this; 
+    }
+
     /*
     protected $properties = array();