Allow option to specify config file

previously, you could either specify a json config as an option, or use
a file of crane.json or crane.yml
Use verbose flag to output the container(s) values

makes it easier when your config is not being handled correctly
fix yaml parsing:  multiple tags must be space-separated, not comma-separated

was ignoring the tag to inform Unmarshall the name of the field for yml
When status command fails, print more debug info
allow the dockerfile specification to use environment vars