--parseable: add newline for every row

Problem: view-user --parseable does not add a newline character for
every row when listing all of the banks that a user belongs to and
instead puts them all on the same line.

Add a newline character for every row that a user belongs to.

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

@@ -142,6 +142,7 @@ def get_user_rows(conn, user, headers, rows, parseable, json_fmt):
         for row in rows:
             for col in list(row):
                 user_str += str(col).ljust(col_width)
+            user_str += "\n"
 
         return user_str