Remove "require" to avoid clash on $extra_packages

[mergwyn]

All classes using ensure_resources have to use the same parameters, so having explicit local dependencies results in a duplicate class definition error. Replace the "require" from the ensure_packages with a chained dependency.

I needed to make the changes to the ensure_packages for ssd as well to make the unit tests run, though I don't understand why this was necessary.

This fixes issue #81

[ghoneycutt]

Fixes #81

[ghoneycutt]

Thanks @mergwyn

Released in 2.13.1