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