to stop animation, use string which has length 0.

Angular-UI's tooltip has a issue about animation from verison 0.7.0.
https://github.com/angular-ui/bootstrap/issues/1418

This is caused by cast miss of string to boolean.
At line 265 on tooltip.js, uses double negative for cast.
But it cast 'false' to true. So I use ''.
use angular-time modified.
restore tracked time when switching.
dont auto start
use minute for manual post
fix position