Fixes for bug 1496

No longer uses a build layer as there are development tools we still
need at runtime.

Changes yq to come from a stable source (PyPI) instead of PPA.

Bug 1496

Change-Id: I0964edc1992c11c459a572ef77cf225f2eebf568
Signed-off-by: beierlm <mark.beierl@canonical.com>