Add "enabled" config option

If a plugin has enabled = false, it will not load.

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

omnibot/bot.py

@@ -19,6 +19,7 @@ class Bot:
         self.__plugins = [
             plugin.load_plugin(server_config, config)
             for config in server_config.plugins
+            if config.get("enabled", True)
         ]
         # TODO - this may not be needed
         self.__channels: Set[str] = set()