Allow users to create, configure and delete their own jobs

Allow admins to setup a jenkins server in a way that lets them avoid becoming the bottleneck to a large development team. Each user is able to create their own jobs and once the job is created the regular authorization rules apply (this works well in combination when repository permissions are enabled). Users can create a new project, configure it with a github url they have rights to, then the repository permissions take over.

The admin page contains a new option "Allow Authenticated to CREATE new jobs". Several different permissions are required to create a new job & do an initial configuration 
* `Item.CREATE` to so the "new job" menu item appears
* `Item.READ`, `Item.EXTENDED_READ` and `Item.CONFIGURE` so the user can do an initial configuration of the new job
* `Item.DELETE` if users can create their own jobs it seems reasonable that they can delete them too.

When enabled authenticated users can CREATE new jobs & then configure jobs to setup the repository so
regular repository level authorization takes effect.