Fix search dropdown

Looking at the JS Console, I see this issue:

Uncaught TypeError: $.camelCase is not a function
    at Collapse.show (bootstrap.js?svv6vg:710:24)
    at Collapse.toggle (bootstrap.js?svv6vg:756:57)
    at new Collapse (bootstrap.js?svv6vg:650:35)
    at HTMLDivElement.<anonymous> (bootstrap.js?svv6vg:797:52)
    at T.each (jquery.min.js?v=4.0.0-beta.2:2:2876)
    at T.fn.init.each (jquery.min.js?v=4.0.0-beta.2:2:1386)
    at T.fn.init.Plugin [as collapse] (bootstrap.js?svv6vg:791:17)
    at HTMLButtonElement.<anonymous> (bootstrap.js?svv6vg:829:12)
    at HTMLDocument.dispatch (jquery.min.js?v=4.0.0-beta.2:2:38062)
    at v.handle (jquery.min.js?v=4.0.0-beta.2:2:36042)

It seems likebootstrap.js is using a function that is deprecated in jQuery around 2016: https://github.com/jquery/jquery/issues/3384

I was able to make the collapse functionality to work by forking the project and adding the missing functions, screenshot:

There's some styling to do and I need to update the README.md file but at least it is working for now.

I applied some changes and It looks much better than It was before, even on mobile:

I'll move it to "Needs Review" but I think this can be moved to "Fixed" soon in order to merge it to the 2.2.x branch and fix some issues related with the search bar.

I just merged it to the 2.2.x branch because I really need the changes for fixing the issue # 3328586