Bug: Default Sortable css classes conflict with other plugins

[b-camphart]

There is a conflict with the Longform plugin due to the use of default Sortable CSS classes for drag/drop behavior see this issue. I've submitted a PR to have Longform use non-default css classes for Sortable, but cMenu still uses them. This will lead to other plugins also having conflicts with cMenu too, or other plugins interfering with cMenu's drag/drop behavior.