[build] Add support to build debian image.

Switch to using github.com src for the kingpin pkg

[README] Minor rewording

[README} Update README

[build] Improve rake task docstring.

[commander] Fix bad import path for distillog.

[build] Update boostrap-dev to include missing 'deboostrap' reqmt.

[build] Remove bundler from Rakefile.

[commander] Fix stats (prometheus) data dir perms.

[build] Tweak how sources.list is populated during image build.

[commander] Add a powerstate controller.

[commander] withMountedPartition takes only name or partition (label).

[commander] Don't use format specifier in Println

[build] Better messages

[build] Ensure cache dir when building debootstrap tarball