Update IrrigationSchedulerApp.groovy

Removes the option to select an optional virtual Irrigation scheduler accessory app and instead looks for scheduler over ride states from the associated device type.  Acceptable over-rides are 
"noEffect"
 "skip" - the scheduler will 1) skip a watering and 2) reset the "effect" value in the device type to "noEffect".   
"onHold"
"expedite"