Replaced Grid.clickable with .viewable.

Clickable grid rows seemed to be more irritating than useful.  Now a view icon
is shown instead.

rattail/pyramid/views/employees.py

@@ -117,8 +117,8 @@ class EmployeesGrid(SearchableAlchemyGridView):
             del g.status
 
         if self.request.has_perm('employees.read'):
-            g.clickable = True
-            g.click_route_name = 'employee.read'
+            g.viewable = True
+            g.view_route_name = 'employee.read'
         if self.request.has_perm('employees.update'):
             g.editable = True
             g.edit_route_name = 'employee.update'