Add scripts to run in a CI-like mode

* tools/cache-prep.sh
* tools/gate-wrap.sh

Change-Id: Id4cf7a010fb2e4a83f656aa96cffc793c4139f09
Combine localrc files

Work out a method to combine devstack-vm-gate.sh's localrc files with ours
to have a way to modify it.

Change-Id: I18cb963c4baeeeb447bcb1436521100f1372882a
Merge branch 'combine-localrc' into dt-test
Merge branch 'tools' into dt-test
Merge branch 'nova-clean' into dt-test