Check params before clearing dataStoreCache (GEOS-6575)

See https://jira.codehaus.org/browse/GEOS-6575 for discussion.

Initial review here https://github.com/geoserver/geoserver/pull/668
As far as I understand a feature type can never change the datastore connection params, since it's created after the store, so that check seems superfluous as best.
As for the sql views yes, you can remove them without affecting the store, but you'll have to write some JDBCDataStore specific code, see the ResourcePool custom code handling them (for the creation side)