Rationalize use of namespace/name.

Address @thockin comment from #1297 about namespace/name being consistent across objects, resources, and labels.

Confined k8s resources to have names which are DNS_SUBDOMAIN format, rather that path.  Since we only have two resources so far, it seemed safe to restrict this space a bit.  FYI @johnwilkes 
 
Also added text to labels doc describing their format.  FYI @bgrant0607 

Also FYI @derekwaynecarr 
I don't know that changing "name" to "label" clarifies anything.  Anyone reading this already has context that we are talking about resource names.

As for DNS_LABEL vs DNS_SUBDOMAIN, we decided that pod names should be SUBDOMAIN.  Is there a problem with it, or just striving for less-is-more?