Add label key namespacing

Allow "name.space/key" format.  Also loosen DNS952 to 1035 (limit 24 -> 63). 
uggh, I didn't realize this would be a point of confusion.  namespace != namespace.  Or more precisely a namespaced label key != a kubernetes API namespace.

What I meant to convey here is that different parts of the system may attach labels or annotations and the way you can tell that is the namespace of the key - more like a vendor code than an api namespace.  Automated components should never add a key without a vendor code, so if we find a key without a prefix, we know the user MUST have created that key themselves.

How can I clarify this?