This change adds a local CLI ./bifrost-cli that allows to easily
run bifrost playbooks. It is targeting early adopters and thus
is opinionated and does not expose all possible options.
Only the very minimum is provided in this patch. More options
will be added later as we decide they are important.
Documentation will also be provided later as it's going to be
quite large. This feature should be considered technical preview
at this point until we give it more testing.
Change-Id: I2205e759431024124518716eccd07f79bda14f3a
12c6f7120f