add public method to refresh schema metadata
allow disabling automatic schema synchronization
update ccm harness
close cluster if available
introduce delayed schema change event processing
utilize schema_refresh_timeout for maximum refresh delay size
update features summary
remove redundant schema refresh de-duplication
[ci skip] update changelog
Merge pull request #46 from datastax/refresh-schema-method

Schema synchronization improvements
randomize host list to prevent hotspots
randomize host list