feat(validate): Support/configure DC/OS accounts and their citests. (s…

…pinnaker#1907)

Also refactored explicit Configurator interface.

chore(build): Add only_publish_changelog flag. (spinnaker#1890)

fix(ha_image_janitor): Tag only published images, not aliased. (spinn…

…aker#1883)

fix(release): Tag halyard once (spinnaker#1859)

fix(build_release): Specify directory to build with GCB. (spinnaker#1852

)

fix(generate_bom): Replace removed config_file. (spinnaker#1811)

fix(validate): fixed location assumptions in tests. (spinnaker#1741)

This still doesnt work in general for aws, though
it does work with my paritcular setup. My intent
here was to be able to easily change the region,
but I still cannot do that. I think this is still
an improvement overall, though doesnt go as far as
I wanted.

feat(bom): Adds utility to reconstruct source from BOM. (spinnaker#1745)

fix(build): Include all subsystems in index. (spinnaker#1710) (spinna…

…ker#1711)

fix(changelog): Sanitize changelog and rename changelog post. (spinna…

…ker#1697)