VOL-41: Moved business logic out of form layer. Refactored form not to receive an 'action' parameter since it's implicit based on other params. Added sanity checks for passed params. Wired up delete button and managed label logic for the create/update button.
Fairly significant refactoring. Moved most Upgrader constants into the classes that they relate to. Introduced parent class CRM_Volunteer_BAO_Activity for custom Activity types, to reduce repetitive code.
VOL-42 bugfix: correct check on URL params for commendation form.
VOL-42: Added star icons to commendation UI.