change default cephdriver log level to debug (since we cannot do it in the drivers.yml stub [#116909649](https://www.pivotaltracker.com/story/show/116909649)
change default cephdriver log level to debug (since we cannot do it in the drivers.yml stub
[#116909649](https://www.pivotaltracker.com/story/show/116909649)

cloudfoundry-incubator/cephfs-bosh-release,cloudfoundry-incubator/cephfs-bosh-release