Use /var/run/crowbar for locking instead of /tmp

Using predictable filenames in /tmp for locking is not secure.
Merge pull request #1911 from cloudedge/pull-req-master-659142f998ec3f393579a94f6beb129b886c15c8

Remove failing tests, make dev tests server add delayed job [2/2]
Merge pull request #1909 from vuntz/fix-chef-client-calls

Use /var/run/crowbar for locking instead of /tmp [2/2]