Custom visibility timeout for each message in SQS queue

First the visibility timeout for each message was set to 0. Now we can set a custom value from 0 to 43200 seconds.12 hours is the maximum. We just need to set it in spring configuration as a property of AmazonAwsSQSConnectorFactory. name="visibilityTimeoutOnReset" value="10"
Make final.  Also add a getter.