Update the kubelet with the ability to register itself with the master.

See #2303
Thanks for adding this doc.  It explains the different options well.  Would you mind either:
 - moving it to docs/design/clustering.md until we have complete support for all the options; OR
 - calling out which options are actually supported, and which aren't, as of the time of this PR being merged.

Ideally, all descriptions in the top level docs folder would be current rather than aspirational.