Available collaborators API: do not include student who issues the request

[#79005958]
Reorganize existing AngularJS code (create cc-portal app)

[#78569994]

Diff may not be very clear, but the main change is that portal-app is
created and added to <body> in application layout. I did it, as there
can be only one ng-app specified per page.

I also renamed ccDirectives to signupDirectives and added cc prefix
to some modules.
Move .control class out of bookmarks stylesheet

[#78570078]
Implement complete create collaboration UI

[#78569994]
Move custom lightbox styles to separate css file

[#78569994]