[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/BackupableDBOptions.java

@@ -0,0 +1,52 @@
+// 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;
+
+/**
+ * BackupableDBOptions to control the behavior of a backupable database.
+ * It will be used during the creation of a BackupableDB.
+ *
+ * Note that dispose() must be called before an Options instance
+ * become out-of-scope to release the allocated memory in c++.
+ */
+public class BackupableDBOptions {
+  public BackupableDBOptions(String path) {
+    newBackupableDBOptions(path);
+  }
+
+  /**
+   * Returns the path to the BackupableDB directory.
+   *
+   * @return the path to the BackupableDB directory.
+   */
+  public String backupDir() {
+    assert(isInitialized());
+    return backupDir(nativeHandle_);
+  }
+
+  /**
+   * Release the memory allocated for the current instance
+   * in the c++ side.
+   */
+  public synchronized void dispose() {
+    if (isInitialized()) {
+      dispose(nativeHandle_);
+    }
+  }
+
+  @Override protected void finalize() {
+    dispose();
+  }
+
+  boolean isInitialized() {
+    return nativeHandle_ != 0;
+  }
+
+  private native void newBackupableDBOptions(String path);
+  private native String backupDir(long handle);
+  private native void dispose(long handle);
+  long nativeHandle_;
+}