Dockerfile must not be in .dockerignore otherwise
you can't run dockerbuild command
Change-Id: I504f3dae20d675fed4bd98bffb33d0b14e9f11f5
Closes-bug: #1515065
This delegates more of the magic to the install script, and also has
some improvements to the Dockerfile and the related documentation.
Closes-Bug: #1461894
Change-Id: I86c0e439b8d0d8f40197fb4a8e26b2655036949c