Add option to build containers in installed ISO

Add kernel parameter build_images=1 to enable Docker image
building, which creates /root/.build_images.
This in turn replaces the option to unpack prebuild Docker
images and load them.

blueprint fuel-master-ci-tests

Change-Id: I07f0ac96b281d593a335793ba7331a8ab7dcc7d1
Merge "Add option to build containers in installed ISO"