JS: Enqueue various BuddyPress JS scripts for BP 2.1.

See:
https://github.com/buddypress/BP-Default/commit/619efe8527847266c961fa43775eade42c7ff70d

In cbox-theme, only the scrollTo script was causing issues with javascript
breaking, but better to enqueue everything just in case!
Add at-mention suggestions support for BP 2.1.

See:
https://github.com/buddypress/BP-Default/commit/b613fda3e844b0af5ed9c1b0d8b7b16e7438da45