redmine 2007 update permissions

Small tweak, not the real fix, to allow a manger to create/edit/delete everything except for users. Only those with admin access can see the users page.

@dlebauer this should allow us to give people permission to work with the inputs, but not have to give them admin rights.
Haotian is in the process of making changes that will make this unnecessary.  The plan is to always display the users link (assuming there is a current_user) but change the controller to display only the currently-logged-in user on the index page unless that user is an administrator.