resource-manager: Add API for event handling

resource-manager: Add API for event handling

On setting a value onto an attribute using resource-manager set API,
that setting event is broadcasted to listeners.

- typedef (*syscommon_resman_resource_event_cb) (int resource_type,
	int resource_id, int attr_id, const void *data, int count)
  : It receives information about attribute value that has been set
    by resource-manager set API.

- syscommon_resman_subscribe_resource_event()
  : It registers callback function and receives associated 'id' that
    represents callback object. The callback function will be called
    on calling set API to the attribute.

- syscommon_resman_unsubscribe_resource_event()
  : It unregisters callback from listening. The 'id' is one that has
    received from the syscommon_resman_subscribe_resource_event().

Change-Id: I38765498521968e5db0c11a5e5d9285b4a4951f2
Signed-off-by: Youngjae Cho <y0.cho@samsung.com>