Correctly preallocate files in universal compaction

Summary: In universal compaction, MaxFileSizeForLevel is ULLONG_MAX. We've been preallocation files to UULONG_MAX size all these time :)

Test Plan: make check

Reviewers: dhruba, haobo, ljin, sdong, yhchiang

Reviewed By: yhchiang

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D18915
sst_dump: Set dummy prefix extractor for binary search index in block based table

Summary: Now sst_dump fails in block based tables if binary search index is used, as it requires a prefix extractor. Add it.

Test Plan: Run it against such a file to make sure it fixes the problem.

Reviewers: yhchiang, kailiu

Reviewed By: kailiu

Subscribers: ljin, igor, dhruba, haobo, leveldb

Differential Revision: https://reviews.facebook.net/D18927
[Java] Add basic Java binding for rocksdb::Env.

Summary: Add basic Java binding for rocksdb::Env.

Test Plan:
make rocksdbjava
make jtest
cd java
./jdb_bench.sh --max_background_compactions=1
./jdb_bench.sh --max_background_compactions=10

Reviewers: sdong, ankgup87, haobo

Reviewed By: haobo

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D18903