Proposal: Initial namespaces proposal

This is based on feedback and discussion that came out of #1017 

There was discussion that the term project may be problematic, so have removed it in favor of namespace.

I think this aligns nicely with the ACL model discussed thus far.

Feedback appreciated.

@erictune @lavalamp @smarterclayton 


is NamespaceID a DNS_LABEL?  If so, call out in doc.  If not, how does one know which "." to split on?

Also, is there a convention for naming things that are not required to be namespaced, such as policies?  empty prefix, that is, a leading dot?