ensure to be able to remove Slack App Settings

lib/form/admin/slackSetting.js

@@ -4,7 +4,7 @@ var form = require('express-form')
   , field = form.field;
 
 module.exports = form(
-  field('slackSetting[slack:clientId]', 'clientId').is(/(\d+)\.(\d+)/).required(),
-  field('slackSetting[slack:clientSecret]', 'clientSecret').required().is(/([0-9a-f]+)/)
+  field('slackSetting[slack:clientId]', 'clientId'),
+  field('slackSetting[slack:clientSecret]', 'clientSecret')
 );