Perform clean up now Angular 2 is out of beta

[timjacobi]

Remove any outdated material after a grace period to give authors the chance to update their resources.

[timjacobi]

Still waiting since RC status was arguably added to early

[danieleteti]

+1

[DeclanPossnett]

+1

[timjacobi]

Yep, about time :)

[timjacobi]

I've started on this. Please point out any material that should be removed because it is outdated.