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 


I think this is trying to make it possible to do a recursive watch on /pods for the scheduler as efficiently as possible in etcd.  Namespaces segment for typical access but the scheduler should be able to (assuming the policy allows it) watch globally)