Added churn tests based on exact-fill test

Refactored code and added churn tests.  ChurnTable fills the table
and then deletes and adds blocks of entries.  ChurnTableMod adds
1000 entries (though this is a test parameter) and then does
modifies of the table that affect about half of the table with
each call.
Merge pull request #1 from dtalayco/caps-churn-tests

Added churn tests based on exact-fill test