Fix users page display error

According bug description, the users page show error
with host and dbs.  The cause of the problem is we can
not only use user_name as id, it is not unique. Now I
changed the id as the combination of user_name and
user_host.

Change-Id: I28136de2b7c79633dd51bdea5d704038c29aa516
Closes-Bug: #1737695

trove_dashboard/content/databases/tables.py

@@ -692,7 +692,8 @@ class UsersTable(tables.DataTable):
         row_actions = [EditUser, ManageAccess, DeleteUser]
 
     def get_object_id(self, datum):
-        return datum.name
+        obj_id = datum.name + "@" + datum.host
+        return obj_id
 
 
 class DatabaseTable(tables.DataTable):

trove_dashboard/content/databases/tests.py

@@ -635,7 +635,7 @@ class DatabaseTests(test.TestCase):
 
         database_id = database.id
         # Instead of using the user's ID, the api uses the user's name. BOOO!
-        user_id = user.name
+        user_id = user.name + "@" + user.host
 
         # views.py: DetailView.get_data
         api.trove.instance_get(IsA(http.HttpRequest), IsA(six.text_type))\