Better handle 'none' option in the list of priorities when creating issues via the JSM portal or via the normal Create button

Currently, if the default priority in the priority scheme is not set (or set to 'none'), JSD Portal will not display 'none' to users as a priority when creating an issue. Instead, JSD will pick up the priority that resides in the middle of the priorities in the priority scheme for that issue type.
For example, if the middle priority is 'medium' but the default is 'none', JSD will show 'medium' priority as the default priority when creating the request.

This creates confusion as some customers expect that 'none' priority should exist in the list and either should not allow the users to create an issue at all until the correct priority is set, or create the issue with 'none' priority so that the priority can be set later

Workaround

1. Chose valid default priority in the default priority scheme (i.e. not 'none')
2. Create "No priority' priority and set it to default