[Java] Add a basic binding and test for BackupableDB and StackableDB.

Summary:
Add a skeleton binding and test for BackupableDB which shows that BackupableDB
and RocksDB can share the same JNI calls.

Test Plan:
make rocksdbjava
make jtest

Reviewers: haobo, ankgup87, sdong, dhruba

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17793

java/org/rocksdb/test/BackupableDBTest.java

@@ -0,0 +1,41 @@
+// Copyright (c) 2014, Facebook, Inc.  All rights reserved.
+// This source code is licensed under the BSD-style license found in the
+// LICENSE file in the root directory of this source tree. An additional grant
+// of patent rights can be found in the PATENTS file in the same directory.
+
+package org.rocksdb.test;
+
+import org.rocksdb.*;
+
+public class BackupableDBTest {
+  static final String db_path = "/tmp/backupablejni_db";
+  static final String backup_path = "/tmp/backupablejni_db_backup";
+  static {
+    System.loadLibrary("rocksdbjni");
+  }
+  public static void main(String[] args) {
+
+    Options opt = new Options();
+    opt.setCreateIfMissing(true);
+
+    BackupableDBOptions bopt = new BackupableDBOptions(backup_path);
+    BackupableDB bdb = null;
+
+    try {
+      bdb = BackupableDB.open(opt, bopt, db_path);
+      bdb.put("hello".getBytes(), "BackupableDB".getBytes());
+      bdb.createNewBackup(true);
+      byte[] value = bdb.get("hello".getBytes());
+      assert(new String(value).equals("BackupableDB"));
+    } catch (RocksDBException e) {
+      System.err.format("[ERROR]: %s%n", e);
+      e.printStackTrace();
+    } finally {
+      opt.dispose();
+      bopt.dispose();
+      if (bdb != null) {
+        bdb.close();
+      }
+    }
+  }
+}