Dead code removal: sos.plugins.common_prefix()

Unused. Delete.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
Dead code removal: PluginException

Defined but never used. Delete.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
Convert infiniband to package list

Remove infiniband's open-coded check_enabled() and use a package
list to control plugin activation.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
Replace self.policy().pkg_by_name() us in Logs plugin

Use self.is_installed() for simple package presence tests.

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>
Clean up package checks in processor plugin

Signed-off-by: Bryn M. Reeves <bmr@redhat.com>