A more restricted interface for HStore. Only gives the caller access to information
about store configuration/settings that cannot easily be obtained from XML config object.
Example user would be CompactionPolicy that doesn't need entire (H)Store, only this.
Add things here as needed.
Gets the cf-specific compaction check frequency multiplier.
The need for compaction (outside of normal checks during flush, open, etc.) will
be ascertained every multiplier * HConstants.THREAD_WAKE_FREQUENCY milliseconds.