Fixed issue with CacheServerNamespaceTest.testBasicCacheServer test case method, finishing/rounding out the work that was done in SGF-218.
Fixes JIRA issue SGF-231 - user is unable to specify Order Policy with Serial Gateway Senders.
Fixes JIRA issue SGF-232 - user is unable to specify Order Policy with a Serial Async Event Queue.  Plus, made additional changes to the GatewaySenderFactoryBean class and associated tests/code for SGF-231.
Fixed failing test cases in the SubRegionSubElementTest class due changes that fixes SGF-231 and SGF-232.
Fixes JIRA issues SGF-230 and SGF-233 involving the persistence on a Async Event Queue or Gateway Sender when a logical Disk Store name has been specified, or the disk-synchronous attribute has been set, requiring persistence to be enabled when all the user wanted was overflow.