Export Google-internal library

Exporting the Google-internal CAP library as submitted at HEAD. Also, fixing the CAP validator to be compatible with it.

The new CAP library has a bunch of new features, bug fixes and validation heuristics. More details to follow in the notes of the upcoming release.
I'm not sure what the policy on versioning is. I'm going from 8 to 10 to keep the library the same version of the validator, but maybe it's not important. Also, maybe I should change this only when I actually release.

But if you are fine with this change, I'll keep it.