Focus Keeper Timer

Implemented:
 - webpage with countdown timer
 - CSS stylesheet, images and audio
 - timer could count in two modes: activity and break. For each mode initial time is hardcoded
 - timer could be paused, resumed and stopped
 - timer play sound: clock ticking
Move FocusKeeper Timer into its own folder
Merge pull request #1 from denis-vilyuzhanin/dev

Introduce version 0.1