Don't print Kubernetes username/password to console.

It is too easy to copy/paste this on-line.

Fixes #1483
Merge pull request #1494 from jbeda/no-password-printing

Don't print Kubernetes username/password to console.
Add an IPAllocator type
Add a flag-compatible wrapper for net.IPNet
Move ErrorList to util
Add a util/exec interface for testing execs.
Add a pkg for iptables support

This makes iptables an injectable dependency.  The test for this started off
simple, but got a bit out of hand.  It's starting to become a mocking
framework.
Use '=' for flags or else parsing gets confused sometimes
Add support for ip-per-service
Print portal IP in kubecfg
Better handling of unbound pods.

A small collection of tweaks to better handle pods when they are not currently
bound to a host.
Add and update docs.