Updated width and positioning of pnotify items

Addressing @SabreCat's issues with #3237:
* Notifications moved down to 60 pixels from top of page. 
* Width set to 250px

Other changes: 
* Notifications are now translucent. 
* Delay set to former value of 7 seconds. 
* Notifications persist if type == error
* Mousing over a notification will not extend the time before it disappears.
* Notifications are now spaced 15px apart.