Docker bug fixes

Merge branch 'docker-exec-by-version' of https://github.com/donaldguy/packer into donaldguy-docker-exec-by-version

Make the Vmware build extract the host IP properly from ifconfig stdout

Fix for VMWare on OSX – MAC address can be upper or lower case

Clarify doubly-nested array use in post-processors

Prepending -i to sudo so PATH is inherited from profile.d scripts

Report error during Temporary Security Group creation in AWS EBS builder

builder/amazon/chroot: fix no attachments on volume error.

code.google.com/p/go.crypto/ssh is now at golang.org/x/crypto/ssh as of
https://code.google.com/p/go/source/detail?spec=svn.crypto.69e2a90ed92d03812364aeb947b7068dc42e561e&repo=crypto&r=8fec09c61d5d66f460d227fd1df3473d7e015bc6

Using the code.google.com import redirects properly, but runs into
issues if you try to use a subpackage of `ssh`, e.g. `agent` which
refers to golang.org/x/crypto/ssh causing conflicts if your types expect
code.google.com/p/go.crypto/ssh.

This is a precursor to a PR for #1066.

packer: skip colored ui test if ui doesn't support colors

contrib: zsh completion

Changes date example in isotime

Fixes #2079 - Documentation parallel_tools_mode / guest_additions_mode