added post-processor-vsphere

builder/vmware: Path related fixes in esx5 driver

/cc @matheeeny - Tests :)

/cc @matheeeny - I prefer to be more explicit and say this is the path,
rather than the secret value itself.

provisioner/chef-solo: add support for chef-solo encrypted data bags

/cc @rasa

post-processor/vagrant: skip gzip compression if compression_level=0

website: fix run-on italicizing for description of data_bags_path

underscore of "data_bags" should be escaped; causes run-on italic

Adds additional option to chef-solo provisioner for an encrypted data bag
secret file.  Local file is copied up and referenced in solo.rb

The initial check in Builder.Prepare does not use the OutputDir interface.
stepPrepareOutputDir also checks if OutputDir exists, error out there unless
using -force so we get the same behavior when RemoteType is esx5.

- Fixes builder/vmware when using RemoteType esx5,
  as there is no longer a local OutputDir

- Fix mkdir of packer_cache in ESX5Driver.UploadISO

- Fix vmx path in ESX5Driver.IsRunning

website: Fix spelling in Intro documentation

core: log golang version in debug output

This introduces a Docker builder. The docker builder is able to create
containers by starting an existing Docker image, provisioning it using
standard practices, and then exporting it using `docker export`.