pop-db: specify arguments to add_user() call

Problem: The pop-db command calls add_user() in order to add users from
a .csv file to the flux-acounting DB, but it does not specify which
args it is passing in the add_user() call. Now that the arguments to
add_user() have changed with the addition of the fairshare argument,
this call in pop-db breaks.

Specify which arguments are being passed to add_user() in pop-db.

src/bindings/python/fluxacct/accounting/db_info_subcommands.py

@@ -86,14 +86,14 @@ def populate_db(conn, users=None, banks=None):
 
                     u.add_user(
                         conn,
-                        username,
-                        bank,
-                        uid,
-                        shares,
-                        max_running_jobs,
-                        max_active_jobs,
-                        max_nodes,
-                        queues,
+                        username=username,
+                        bank=bank,
+                        uid=uid,
+                        shares=shares,
+                        max_running_jobs=max_running_jobs,
+                        max_active_jobs=max_active_jobs,
+                        max_nodes=max_nodes,
+                        queues=queues,
                     )
         except IOError as err:
             print(err)