[1111064] Some code changes to avoid a locking issue.  Presumably the
issue has to so with passing an attached entity to an asynchronous slsb
method.  A few things:
- make sure we pass a deteched entity
- notify the alert condition-cache prior to calling the storage operation hook
- only call the storage operation hook for updates to existing history (not
  at operation schedule-time)
- remove an unnecessary outer Tx on runClusterMaintenance
- add some logging

Note: TODO: revert the hyped up scheduling of the cluster readrepair job
revert testing change to StorageClusterReadRepairJob, put it back to the
original schedule.
Merge pull request #90 from rhq-project/jshaughn/1111064

[1111064] Some code changes to avoid a locking issue.