Add notifier that executes custom command when episode is added to library

This plugin enables the execution of a custom command (as the sickbeard user) when an episode file is added to the library, to allow for easy scripting of custom actions (I use it for notifications on IRC and notifying a custom Android app, for example).

There are ofcourse security risks involved; that's why this plugin won't work without the user explicitly editing a line in config.ini. This is clearly stated, including the risks involved, on the configuration page.

On the to-do list would be adding the ability to execute custom commands on other types of events, as well as customizing the (order of) the command-line arguments.