TODO -handle reset, it should stop the count down✅ -figure out why pressing play more than once speeds up the timer count✅ (overlapping setIntervals) -implement pause ✅ -why is intervalId returning num? -play button when pressed for the first time enteres pause by default -switch to break time when session expires

1. When I click the element with the id of "reset", any running timer should be stopped, the value within id="break-length" should return to 5, the value within id="session-length" should return to 25, and the element with id="time-left" should reset to it's default state.

2. When a break countdown reaches zero (NOTE: timer MUST reach 00:00), and a new countdown begins, the element with the id of "timer-label" should display a string indicating a session has begun.