Ask user for reconfirming when deleting key objects

Current implementation of all object deleting operation of heatclient doesn't need user to reconfirm,
so user doesn't have the chance to recheck their deleting operation,
this may cause user deletes objects which they originally don't want by accident,
especially for those objects can be deleted by providing object name, such as stack.
A reconfirming step could be add to avoid this situation, for some key heat objects.