add brief clock
the container and adapter begins to work
temp commit
add a test activity to make brief clocks
improve the touch events

- make sure the touch point is within the circle
- distinguish `touch` and `drag` by setting a minimum dragging
  distance
- perform click when ACTION_UP is triggered
Enlarge the circle when dragging up
drag down with fading out
make drag down to remove the clock
add "add" at the end of BriefClockContainer
make "add" button work
draw the add button view
merge BriefClockContainer into SettingActivity

- color of BriefClock is adjusted
- the text is better aligned (vertically center)