Collapsible vmousecancel

Hi. This is not easy to reproduce bug but when you check this code, it makes more sense :)

It works only on mobile browsers, where tap event is called.
Test page: http://jsbin.com/ujudog/1/
Code: http://jsbin.com/ujudog/1/edit
Before: 
![merge0](https://f.cloud.github.com/assets/411343/642073/0f84467c-d34c-11e2-9e28-266b7d94190e.png)

1. Double tap  on "Heading"
2. Make sure your second tap is finished (move your finger) outside "Heading".
3. If collapsible didn't expand, it worked.
4. "Heading" should have ui-btn-active class (blue):
![merge2](https://f.cloud.github.com/assets/411343/642070/ea3a19b4-d34b-11e2-8def-c28a0ba3e73f.png)


This happens, because ui-btn-active class is removed only on expand/collapse event. When user triggers only tap and mousecancel, this class is not removed.
I added test case but it just tests that vmousecancel removes this class.