Templates modal converted to bootstrap

Same as #4575 #4563 #4562 #4561 #4514 #4513

Tests:
Follow the images to navigate:
![screenshot 2014-10-12 23 29 30](https://cloud.githubusercontent.com/assets/3889375/4607439/b3fc7364-524e-11e4-86d7-45230a611fbc.png)
![screenshot 2014-10-12 23 29 44](https://cloud.githubusercontent.com/assets/3889375/4607440/b7611c30-524e-11e4-90b9-d1036f1319e5.png)

And:
![screenshot 2014-10-12 23 29 58](https://cloud.githubusercontent.com/assets/3889375/4607441/ba0c1f16-524e-11e4-9f21-5d728f997c64.png)
![screenshot 2014-10-12 23 30 13](https://cloud.githubusercontent.com/assets/3889375/4607442/c1f354ce-524e-11e4-8448-3b4f11b424b0.png)

Reading the specs of the preview image:
A thumbnail preview image should be 206 pixels in width and 150 pixels high
A preview image should be 640 pixels in width and 388 pixels high
Popover will get meshy with this image size.
You think that modal with `<iframe class="iframe" src="/templates/beez3/template_preview.png” ` is unacceptable?