Add a NewStringSet() function

Also beef up tests to cover len(ss).
Merge pull request #289 from thockin/cleanups

Add a NewStringSet() function
Add a link to the I/O talk on YouTube
Fix the link.
Reduce logging noise

Don't use %#v for errors.
Do use %+v when more detail than %v is needed.
Fix typos Kublet -> Kubelet.
Move scheduler to own package.
Fix up usage and tests, split into multiple files.

Doing this in multiple commits in an attempt to preserve the file movement history.
Add crash handler bypass for testing.
Add a doc on collaborative development
Merge pull request #290 from thockin/logging

Reduce logging noise
Merge pull request #292 from thockin/docs

Add a doc on collaborative development
Fix line break
Merge pull request #303 from thockin/docs

Fix line break
pkg/registry now passed race detector.
use mutex instead of rwmutex
Merge pull request #306 from monnand/registry-race

Solved data races in pkg/registry
Break the dep from util -> api

Part 1 in a series of changes towards data validation.
fix data races in controller
Add validation primitives to util

Part 2 in a series of changes towards data validation.
Merge pull request #308 from thockin/valid2

Break the dep from util -> api