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
Yueh-Hsuan Chiang