broker/MapDBPersistentStore: Interfaces used for the Constructors

broker/IStore: Interface added for MapDBPersistentStore
broker/ProtocolProcessorBootstrapper: class loader for store added
broker/ISessionsStore#mapToGuid: moved to IMessagesStore
broker/ProtocolProcessorBootstrapper: getter used for SessionStore
broker/Server: getter for processor added
broker/ProtocolProcessor: getter added for Stores

broker/src/main/java/io/moquette/spi/IMessagesStore.java

@@ -142,4 +142,6 @@ public interface IMessagesStore {
     void cleanRetained(Topic topic);
 
     int getPendingPublishMessages(String clientID);
+
+    MessageGUID mapToGuid(String clientID, int messageID);
 }