OAK-1560: Expose RevisionGCMBean for supported NodeStores
Only require an Executor instead of an ExecutorService in the constructor of RevisionGC

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1579613 13f79535-47bb-0310-9956-ffa450edef68
OAK-1559: Expose BlobGCMBean for supported NodeStores
Only require an Executor instead of an ExecutorService in the constructor of BlobGC

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1579614 13f79535-47bb-0310-9956-ffa450edef68