ISPN-4225 Upgrade to JGroups 3.5.0.Beta5
ISPN-4190 Use Message.Flag.DONT_LOOPBACK instead of RequestOptions.setExclusionList

DONT_LOOPBACK is now a transient flag
Use waitForRehashToComplete() instead of waitForClusterToForm() when killing a node

waitForClusterToForm() will fail if it sees too many members, see ISPN-4194
ISPN-4231 DistSyncL1FuncTest.testRemoteGetArrivesButWriteOccursBeforeRegistration random failures

Restart the cache after each method, to prevent commands from the previous
test method from interfering.

Should also fix ISPN-4133 DistSyncL1FuncTest.testNonOwnerRetrievesValueFromBackupOwnerWhileWrite
On exception RESTHelper would get into NPE rather than providing helpfull details as the catch code seems intentioned to do