[meta] Port deploy to Drupal 8

#1540656: [META] Entity Serialization API for web services (e.g. content staging) is now Fixed!. Would be great to sketch out a plan for D8 soon.

Anyone curious about this might want to watch dixon's killer presentation at Drupalcon Austin. See https://austin2014.drupal.org/session/content-staging-drupal-8. Or if you read this after October 2014, see Amsterdam video at https://amsterdam2014.drupal.org/session/content-staging-drupal-8-continued

Short update:

Work is going on in the Multiversion and Relaxed Web Services module that'll provide the base for Deploy in Drupal 8. All the work and issues are tracked in the respective d.o issue queues, but we're currently developing on Github (for Travis CI integration) and merging occasionally to the repositories on d.o. The Github repositories are:

• https://github.com/dickolsson/drupal-multiversion
• https://github.com/dickolsson/drupal-relaxed

Closing this as a duplicate of the contrib_tracker issue here: #2608242: [deploy] Deploy module
That issue will probably receive more visibility now when it integrated with project pages here on drupal.org.