Now the tests are ran against the actual docker engine instead of
against mockerode.
The new tests actually caught a bug in
`volumeManager.removeOrphanedVolumes`, where that function would try to
remove volumes for stopped containers, causing an exception.
This commit also fixes that bug.
This also needs to modify the test environment as database migrations
will look for `config.json` in the location given by the variable
`CONFIG_MOUNT_POINT`.
The volume tests now run against the actual docker engine setup via dind
Change-type: patch
