detect latest version of coreos
more robust coreos checking
Merge pull request #2985 from eugeneware/latest_coreos_support

guests/coreos: detect latest version.
core: copy all sub-directories in a box properly

This avoids an Errno::EACCES on windows, although I'm really unsure why.
core: disable parallelization if only one action
provisioners/chef: DRY and unify encrypted data bag secret handling

Pull up encrypted data bag secret management into the base classes, thus
also unifying the functionality.

Especially this complements the issues:
  * Upload the secret to provisioning path also with chef-solo [GH-1246]
  * Delete the secret also with chef-client [GH-2712]
  * Remove the secret before uploading also with chef-client [GH-1111]
provisioners/chef: set `encrypted_data_bag_secret` to `nil` if it's not uploaded

/cc @shanegibbs

Fixes #2984
website/www: use absolute links in the feed

Some feed readers, like FeedBurner[1] don't support content
that uses relative links. This just makes them absolute so they
will work everywhere.

[1]: https://support.google.com/feedburner/answer/79018?hl=en
Merge pull request #2996 from pearkes/website-rss-absolute

website/www: use absolute links in the feed
kernel/v2: fix error where options could be not hash
Depend on ChildProcess 0.5.0, fix bugs
website/docs: fix typo [GH-2998]

Fixes #2998
Merge pull request #2845 from tmatilai/chef_data_bag_secret

provisioners/chef: DRY and unify encrypted data bag secret handling
Update CHANGLEOG

[ci skip]
website/www: feature preview boxes 2.0