Revert "Revert "Add support for stopping a proxier.""

This reverts commit 19beaf71b576b557f65960ec35086b9580a91221.
Add custom conversion function system.

As an example, demonstrate how Env.Key's deprecation ought to work.
Slightly pause on requests to allow most to finish

Currently, every write will result in a 202 (etcd adding a few
ms of latency to each request).  This forces clients to go into
a poll loop and pick a reasonable server poll frequency, which
results in 1 + N queries to the server for the single operation
and adds unavoidable latency to each request which affects their
perception of the service.

Add a very slight (25ms by default) delay to wait for requests
to finish.  For clients doing normal writes this reduces the
requests made against the server to 1.  For clients on long requests
this has no effect.  The downside is that http connections are held
on to for a longer period in high write loads.  The decrease in
perceived latency from the kubecfg is significant.
Fixed tests.
Test both directions of the conversion.
Add a comment to tickle travis.
Merge pull request #672 from lavalamp/customConversionFuncs

Custom conversion funcs
Merge pull request #706 from brendandburns/proxy

Revert the revert and fix tests.
Add RestartPolicy to Pod and PodTemplate
Merge pull request #691 from dchen1107/restart

Add RestartPolicy to Pod and PodTemplate
Merge pull request #683 from smarterclayton/slightly_pause_on_return

Slightly pause on requests to allow most to finish