Support node label update.
Add more validation for updating node.
Documentation improvements. Fixes #2004, #2115, #2171.
Merge pull request #2423 from bgrant0607/docfix

Documentation improvements. Fixes #2004, #2115, #2171.
Merge pull request #2397 from ddysher/node-label

Support node label update
Add the 0.5 release.
Add the 0.5-dev tag.
Fix namespace of minion birthcry event.
Merge pull request #2426 from brendandburns/release

Release 0.5
Chmod the right file in cluster/vagrant/util.sh

Most of platforms use ~/.kubernetes_auth, but Vagrant is different.
This commit fixes one instance where a setup script did not take this
difference into account.
Merge pull request #2429 from erictune/fix_birthcry

Fix namespace of minion birthcry event.
Add pod restart policy validation for replication controller.
Merge pull request #2433 from ddysher/rc-restart-policy

Add pod restart policy validation for replication controller.
Merge pull request #2430 from rlarocque2/vagrant_auth_fix

Chmod the right file in cluster/vagrant/util.sh
update AWS for the 0.5 release.
Implements a credentialprovider library for use by DockerPuller.

This change refactors the way Kubelet's DockerPuller handles the docker config credentials to utilize a new credentialprovider library.

The credentialprovider library is based on several of the files from the Kubelet's dockertools directory, but supports a new pluggable model for retrieving a .dockercfg-compatible JSON blob with credentials.

With this change, the Kubelet will lazily ask for the docker config from a set of DockerConfigProvider extensions each time it needs a credential.

This change provides common implementations of DockerConfigProvider for:
 - "Default": load .dockercfg from disk
 - "Caching": wraps another provider in a cache that expires after a pre-specified lifetime.

GCP-only:
 - "google-dockercfg": reads a .dockercfg from a GCE instance's metadata
 - "google-dockercfg-url": reads a .dockercfg from a URL specified in a GCE instance's metadata.
 - "google-container-registry": reads an access token from GCE metadata into a password field.
Some small aws refinements.
Merge pull request #2409 from mattmoor/master

Implements a credentialprovider library for use by DockerPuller.
Remove deprecated nsinit from the node definition.
Merge pull request #2436 from brendandburns/salt

Remove deprecated nsinit from the node definition.