Add docker staging code paths

Use existing detected start command fields until upstream changes to support structured metadata

[#75217010]

Signed-off-by: Peter Parente <pparent@us.ibm.com>
Adjust code/tests for new metadata fields post rebase

[#75217010]

Signed-off-by: Stewart Nickolas <nickolas@us.ibm.com>
bump godep for docker runtime-schema

[#75217010]
wip stager templates
actually use the dockercircuefilename
Updated docker_stager cache to use "docker" instead of stack