composer.json - joomla-console - Use totten/master-buildkit. Cleanup other deps.
joomla-demo - Multiple changes:

 * Separate download & install phases
 * Change directory structure so that all source is under WEB_ROOT
   * WEB_ROOT/joomla -- The Joomla directory (was: WEB_ROOT)
   * WEB_ROOT/src/civicrm -- The CiviCRM directory (was: PRIVATE_ROOT/src/civicrm)
   * (This fixes an issue where "civibuild reinstall" destroyed PRIVATE_ROOT and thus all civi src)