Further separate module agents and module impl

Add Omnibot.Module.Agent which implements the basic agent cfg + state
persistence functionality, which is then included in the Omnibot.Module.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

lib/module/base.ex

@@ -32,7 +32,6 @@ defmodule Omnibot.Module.Base do
     quote do
       alias Omnibot.{Irc, Module}
       import Omnibot.Module.Base
-      require Logger
 
       @behaviour Module.Base