Eliminate several warnings

deps/rabbitmq_cli/lib/rabbitmq/cli/ctl/commands/help_command.ex

@@ -17,6 +17,7 @@
 defmodule RabbitMQ.CLI.Ctl.Commands.HelpCommand do
 
   alias RabbitMQ.CLI.Ctl.Helpers, as: Helpers
+  alias RabbitMQ.CLI.ExitCodes,   as: ExitCodes
 
   @behaviour RabbitMQ.CLI.CommandBehaviour
   @flags []

deps/rabbitmq_cli/lib/rabbitmq/cli/ctl/table_print.ex

@@ -96,10 +96,11 @@ defmodule RabbitMQ.CLI.Ctl.TablePrint do
   end
 
   defp dividing_line_length(field_widths) do
-    field_widths
+    n = field_widths
     |> Tuple.to_list
     |> Enum.sum
-    |> + (@n_app_divider_space * num_dividers(field_widths))
+
+    n + (@n_app_divider_space * num_dividers(field_widths))
   end
 
   defp num_dividers(field_widths) do

deps/rabbitmq_cli/lib/rabbitmqctl.ex

@@ -191,7 +191,7 @@ defmodule RabbitMQCtl do
         HelpCommand.print_base_usage(command)
       false ->
         HelpCommand.all_usage()
-        ExitCodes.exit_usage
+        exit_usage
     end
 
     result