Added prevent event 'timer-stopped' on elements selected 

Hi 

I have several timers running in the same time with different values and when every timer has ended,  the event 'timer-stopped' is triggered for every one. I needed that only one specific timer was the responsable to trigger this event.

Also I needed to know the current values on seconds to make some calculations, so I added the method "getCurrentTime ()" to get that values.

Just wondering if you want to consider add this to your project. sorry is my first fork :(