configure method
Configure the this instance of a Carp Service.
The app
specifies the CAWS instance used.
If study
is specified, this service is 'tied' to this study deployment.
This is convenient if the application using this service is only handling
one study deployment (which is often the case).
Implementation
void configure(CarpApp app, [SmartphoneStudy? study]) {
_app = app;
this.study = study;
}