Add scheduling specific task on sucess/error

 * Fix get task properties, get task in DSL
 * Evaluating task on success/error/finish properties in engine:
   - evaluate YAQL conditions
   - schedule tasks
 * Unit tests for handling success/error/finish

 * For real work with context there is need to store
   it somewhere

Implements: blueprint schedule-tasks-after-completion

Change-Id: Ia9c34e755055ff0273dcd79a314858dbfbcc2fa9