Add methods to provide supported views for ComplexObsHandler

Per this dicussion, add the following methods to the ComplexObsHandler Interface:

/* Return true if given view is supported by this handler */
public boolean supportsView(String view);

/* Return all views supported by this handler */
public String[] getSupportedViews();

The ComplexObsHandler can be found in the openmrs-api maven module as org.openmrs.obs.ComplexObsHandler. It is an interface, so it does not need any business logic in the interface.

After adding these methods, update the wiki page.