Do not suggest admin as a default username

Red Herring Error Message:  DateTime::__construct(): Failed to parse time string (jerror) at position 0 (j): The timezone could not be found in the database 

when failing to make a folder on installing an extension.

Looks like one of the commas should have been a period to concat the error message, other error messages are passed through JText::_ but this one is not, and the language string has no place for the path so looks like someone just removed JText::_ call but left in the comma.

All this PR does is remove the comma.


There are a lot of posts about this in the forum, and blog posts. Most give incorrect/false solutions.

Ref:  http://sos82.net/coding/8-joomla-3-0-error-about-datetime-while-create-folder.html