civibuild - If OFFLINE is set, then skip cache updates
civibuild - Enforce timeout when updating git/svn caches

We sporadically encounter issues where "git fetch" hangs.
INFRA-124 - civibuild - Generate/save SITE_TOKEN

This will be useful for validating the Webtests' DSN cookie
INFRA-124 - civibuild - Allow injecting options into civicrm.settings.php for CiviTest
INFRA-124 - civibuild - Allow injecting pre or post settings (via civicrm.settings.d, drupal.settings.d, etc)
INFRA-124 - civibuild - Add clone-create, clone-show, clone-destroy (skeletal code)
INFRA-124 - civibuild - Extract function _amp_snapshot_restore()
INFRA-124 - civibuild - Implement civibuild_clone_create, civibuild_clone_show, civibuild_clone_destroy
INFRA-124 - civibuild - When destroying a build, also destroy any cloned DBs
_amp_install_* - Fix concurrency bug
composer.json, composer.lock - Add phpunit
INFRA-124 - When using paratest, automatically setup multiple DBs using "civibuild clone-create"