This command prints out the components of a template, and most
importantly respects the machine-readable flag so that you can
programmatically inspect a template's contents without manually parsing
the JSON.

/cc @markpeek

This just kind of shields the error with StartWithUi if we retry

builder/amazon/common: added passing UserData to goamz.

/cc @rgarcia

This adds the -machine-readable flag to Packer which turns all output
into machine-readable format. This is documented within the website
source.