Custom Command Trigger

[maltfield]

Goal: Add a text input field where a user can type a command that BusKill will execute in addition to the trigger

Bonus additional changes to make this useful:

1. Add "None" option to triggers (so it will neither lock the screen nor shutdown the computer, if the user wants to only execute their custom trigger)

2. Add "delay" option (unit = milliseconds) that will delay the execution of the main trigger (eg so the user's custom command can have time to make an HTTP query that will initiate a remote dead man switch before shutting down their computer)