Merge pull request dCache#67 from Toilal/fix-commit-response

nfs4: set response committed value properly in op COMMIT based on VFS WriteResult return value

core/src/main/java/org/dcache/nfs/v4/OperationWRITE.java

@@ -89,7 +89,7 @@ public void process(CompoundContext context, nfs_resop4 result) throws ChimeraNF
         res.status = nfsstat.NFS_OK;
         res.resok4 = new WRITE4resok();
         res.resok4.count = new count4(writeResult.getBytesWritten());
-        res.resok4.committed = stable_how4.FILE_SYNC4;
+        res.resok4.committed = writeResult.getStabilityLevel().toStableHow();
         res.resok4.writeverf = context.getRebootVerifier();
 
     }