Migrating to bootstrap-3.1.1

I created a vendor directory in media folder in which I added Bootstrap-3.1.1 directory, jquery-1.11.0 and in which I moved less.min.js

I changed some templates in order to fits the migration guide to version 3 <http://www.bootply.com/bootstrap-3-migration-guide>(essentially classes:`container-fluid` and `modal`)

Removed old bootstrap folder and included askbot and bootstrap less files in style.less in the media folder.

Removed jquery-1.7.2 and changed script calls to  jquery-1.11.0 and
jquery migrate plugin(however there's no warnings from the plugin)

Lastly, I changed DOCTYPE declaration to `<!doctype html>`
Merge pull request #1 from BenjaminABEL/bootstrap-3.1.1

Migrating to bootstrap-3.1.1