Changed PrimaryStorageDownloadCommand/SnapshotCommand to be executed in sequence.

core/src/com/cloud/agent/api/SnapshotCommand.java

@@ -97,7 +97,7 @@ public class SnapshotCommand extends Command {
      */
     @Override
     public boolean executeInSequence() {
-        return false;
+        return true;
     }
 
 }

core/src/com/cloud/agent/api/storage/PrimaryStorageDownloadCommand.java

@@ -57,6 +57,6 @@ public class PrimaryStorageDownloadCommand extends AbstractDownloadCommand {
     @Override
     public boolean executeInSequence() {
     	//Temporary relaxing serialization
-        return false;
+        return true;
     }
 }