Dependency on pinned, old version of sysctl

[bablakely]

Currently this cookbook depends on sysctl 0.9.0, due to this issue: Sous-Chefs-Boneyard/sysctl#100.

If I understand the issue correctly:

The sysctl cookbook now creates individual sysctl.d files for various items, instead of merging them all into /etc/sysctl.conf. @artem-sidorenko 's suggested workaround, since the upstream PR is not getting any attention, is to remove any files or changes made by os-hardening to sysctl's configuration that were in the old scheme, and then allow it to update with the new scheme. However, the challenge is that sysctl.conf (which may exist otherwise and have unrelated items in it) cannot simply be removed, and thus any os-hardening-created modifications must be stripped out.

[bablakely]

Upon further inspection, sysctl.conf is uninvolved, and all that was needed is to remove the file in node['sysctl']['conf_file'] since this attribute is no longer used by sysctl and the necessary configuration should already be re-created in the new location. Sanity check on that would be appreciated, but I believe it's that simple.