File.join -> PathUtils.join

Convert File.join to PathUtils.join in the vhost plugin
Add logging about idling/unidling in vhost plugin

Add logging about idling/unidling in the vhost plugin. Attempting to
determine what's going on with bug 1161165.
Merge pull request #5940 from ncdc/bug/1161165-missing-idler-conf

Merged by openshift-bot