Fixes bug introduced by D6251

Summary: Casting the defaul custom field storage to an int, need to stop that!

Test Plan:
Use some custom fields, make sure they work as expected.
Fixes T3444

Reviewers: epriestley, mbishopim3

Reviewed By: mbishopim3

CC: aran, Korvin, mbishopim3

Maniphest Tasks: T3444

Differential Revision: https://secure.phabricator.com/D6282

src/applications/maniphest/auxiliaryfield/ManiphestAuxiliaryFieldDefaultSpecification.php

@@ -205,8 +205,10 @@ class ManiphestAuxiliaryFieldDefaultSpecification
       case self::TYPE_USER:
       case self::TYPE_USERS:
         return json_encode($this->getValue());
-      default:
+      case self::TYPE_DATE:
         return (int)$this->getValue();
+      default:
+        return $this->getValue();
     }
   }