[Java] Fixed the Java compilation error caused by PlainTableFactory API change.

Summary: Fixed the Java compilation error caused by PlainTableFactory API change.

Test Plan:
make rocksdbjava
make jdb_bench
cd java;./jdb_bench.sh

Reviewers: sdong, ljin, ankgup87, swapnilghike, zzbennett, rsumbaly, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D20295
Fix db_bench

Summary: Adding check for zero size index

Test Plan: ./build_tools/regression_build_test.sh

Reviewers: yhchiang, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D20259
improve comments for CrateRateLimiter()

Summary:
Suggested by @dhruba from the other diff, here is the improved
comments for parameters of the function

Test Plan: none

Reviewers: dhruba, sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D19623