BlockBasedTableConfig Filter policy support RocksJava

As proposed by yhchiang the filter can now be set in Java for
a BlockBasedTableConfig instance.
FilterTest
Merge pull request #330 from fyrz/setFilterPolicyForBBTConfig

BlockBasedTableConfig Filter policy support RocksJava
Fix build_tools/version.sh
Don't return (or dereference) dangling pointer
Merge pull request #333 from nbougalis/cleanups

Don't return (or dereference) dangling pointer
perf_context.get_from_output_files_time is set for MultiGet() and ReadOnly DB too.

Summary: perf_context.get_from_output_files_time is now only set writable DB's DB::Get(). Extend it to MultiGet() and read only DB.

Test Plan:
make all check
Fix perf_context_test and extend it to cover MultiGet(), as long as read-only DB. Run it and watch the results

Reviewers: ljin, yhchiang, igor

Reviewed By: igor

Subscribers: rven, leveldb

Differential Revision: https://reviews.facebook.net/D24207
Add number of records dropped in compaction summary

Summary:
Add two stats to compaction summary:
1. Total input records from previous level
2. Total number of records dropped after compaction

Test Plan: See outputs of printing when runnning locally

Reviewers: ljin, igor, MarkCallaghan

Reviewed By: MarkCallaghan

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D24411
Fix lint errors in java/rocksjni/options.cc

Summary:
Fix lint errors in java/rocksjni/options.cc

Test Plan:
make rocksdbjava
Fix a check in database shutdown or Column family drop during flush.

Summary:
Fix a check in database shutdown or Column family drop during flush.

Special thanks to Maurice Barnum who spots the problem :)

Test Plan: db_test

Reviewers: ljin, igor, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D24273
OpenReadOnly support in RocksJava

Changes:
- new Method: RocksDB openReadOnly(String path)
- new Method: RocksDB openReadOnly(Options options, String path)

Missing:
- Column family support is blocked by #319