Add Rackconnect support to openstack builder

ec2-upload-bundle uses deprecated parameter

Tell people to use OVF v2

Updated doc with config

builder/digitalocean: fix response decoding after api changes

[skip ci]

website: address spelling mistakes

The example error message being in here is important so people can search for that error message and find the answer easily. The default in my VirtualBox is V1, so many people will run into this.

This adds two config options that we need in order to successfully build
our Rackspace images.

First, a boolean `rackconnect_wait` option which waits for the
RackConnect metadata to appear.

Second, an `ssh_interface` option, for rackconnect users who have more
prohibitive firewalls on the 'public' interface and want to ensure all
traffic to the server goes over the 'private' one.

Finishes #952.

fixing version numbers: RCs should be labeled x.x.x-rcx

make it clear that "tools_upload_folder" is not used for esxi
[skip ci]

Fix typo in log statement

Support user variables for missing OpenStack string config options

Fixes #1506 

Boot command section in vmware and virtualbox ISO wasn't working
[skip ci]

builders/googlecompute: made formatting consistent

Also updated Debian 7 VM image to `debian-7-wheezy-v20150127`.

builders/googlecompute: fixed link in docs.

Clarify error message in case of an atlas client connection failure

When a packer json contains an atlas postprocessor, and `packer validate` runned locally
in case of the missing ATLAS_TOKEN env var, the following error message is displayed:

* Error initializing client: authentication failed

It wasn't clear which plugin produced this message, so the amazon-ebs builder was the suspect

Add Atlas post-processor documentation

see conversation with ryanuber: https://github.com/hashicorp/go-checkpoint/issues/2#issuecomment-73199209

Signed-off-by: gnawhleinad <danielleehwang@gmail.com>

Update Push APIs

This allows children to get the raw templates without re-reading the
file.