Reduce logging noise

Don't use %#v for errors.
Do use %+v when more detail than %v is needed.
Fix typos Kublet -> Kubelet.
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.
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
Add a FileServer for master's logs
Clarify and lighten the LGTM policy.
Merge pull request #315 from thockin/docs

Clarify and lighten the LGTM policy.
Merge pull request #313 from dchen1107/fileserver

Fileserver
Merge pull request #311 from thockin/valid3

Add validation primitives to util
First cut at input validation for Kubelet

* Add some util functions for basic validation
* Spec api fields more tightly
* Break a dep from util -> api, so I can do the reverse
* Add functions to validate structures
* Call those functions when running manifests

This does not validate as it unmarshals YAML or JSON because I want to be able
to validate structures that come from other inputs without forcing them to be
YAML.

This does not handle all api structures - I am not familiar wnough with the
rest to spec them this tightly - I hope someone else can do that.

There are a number of open questions, marked "FIXME".  Please offer feedback
or opinions.
Fix comments on the WIP change.

* Use strings.Repeat()
Use util.StringSet in validation