workaroud for extra click event in ie 11.

ie 11 has similar issue as FF 20, the extra click causes the container close all x-editor form. You can repro the issue by trying "Select2 (dropdown mode)" on http://vitalets.github.io/x-editable/demo-bs3.html by ie 11. Below is the screenshot for this issue.
![ie11screenshot](https://cloud.githubusercontent.com/assets/469742/2748265/2be0be82-c7b5-11e3-9d08-12deffa213c3.png)