Implements JIRA improvement SGF-281 involving the addition of logic in SDG to avoid setting the Disk Store Name on the RegionAttributes used to a create a Region in the RegionFactoryBean when the Region is neither 'persistent' nor has an Eviction policy of Overflow To Disk. GemFire erroneously throws an IllegalStateException when the Region references a Disk Store but is not configured with persistence or overflow, which should not matter. Also fixed JIRA issues SGF-282 where the Eviction 'action' is ignored for PARTITION Regions when the 'threshold' is not set.