server: Fix forward merge missing import causing build failure

This fixes forward merge regression that missed an import and causes
build failure in b2b99ca

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>

Author: yadvr

server/src/main/java/com/cloud/vm/UserVmManagerImpl.java

@@ -302,7 +302,7 @@
 import com.cloud.vm.snapshot.VMSnapshotManager;
 import com.cloud.vm.snapshot.VMSnapshotVO;
 import com.cloud.vm.snapshot.dao.VMSnapshotDao;
-
+import com.google.common.base.Strings;
 
 public class UserVmManagerImpl extends ManagerBase implements UserVmManager, VirtualMachineGuru, UserVmService, Configurable {
     private static final Logger s_logger = Logger.getLogger(UserVmManagerImpl.class);