CoreOS Rename

Support the rename of CoreOS to Container Linux by CoreOS.

v1.2.1 (2016-11-15) (Azure China only)

• Add support for Azure China by modifying the download URLs to point to the
  mirrors hosted by mirror.azure.cn (gh#112)

v1.2.0 (2016-08-19)

• Fix: On CentOS start dockerd as -H=unix:// instead of -H=fd:// as get.docker.com
  install script has removed socket activation. (gh#104)
• Prefer 'dockerd' in systemd unit files over 'docker daemon'. docker-engine has
  migrated to this. This is why we are releasing a minor version for the extension
  this time and not a hotfix so that existing VMs don’t automatically get this and
  old versions of docker will not work with dockerd.

1.1.1606092330 (2016-06-09)

• Introduced compose-environment public configuration to pass additional unencrypted
  environment variables to docker-compose for fine tuning. (#87, #85)
• Better error messages for docker-compose failures indicating the log path. (#86)

1.1.1604142300 (2016-04-14)

• Fix: docker v1.11 release has broken docker-compose 1.5 from pulling private images.
  Upgrading to docker-compose 1.6.2 and dropping support for docker-engine <1.9.1 (#80)

1.1.1602270800 (2016-02-28)

• Fix: extension crash while collecting “yum install” output (centos/rhel)

1.1.1601140348 (2016-01-13)

• Fix: eliminate redundant restarts of docker-engine on CoreOS if configuration
  is not changed.

1.1.1601070410 (2016-01-06)

• Fix: eliminate redundant restarting of docker-engine. This avoids restart of
  docker-engine service (and thus containers) when (1) VM boots (2) waagent
  calls extension's enable command in case of GoalState changes such as Load
  Balancer updates.
• Fix: Write .status file before forking into background in 'enable' command.
  This is a workaround for waagent 2.1.x.

1.1.1512180541 (2015-12-17)

• Security fix: prevent clear-text registry credentials from being logged.

1.1.1512090359 (2015-12-08)

• Introduced secure delivery of secrets through "environment" section of
  protected configuration to be passed to docker-compose. Users do not have
  to embed secrets in the "compose" section anymore.