Minor tidyup and use Java 7 for file copying
Make sure to use the correct Java classloader for loading the RocksDB
Native Library
Merge pull request #402 from adamretter/bugfix-native-library-loader

Use correct classloader in Java NativeLibraryLoader
Fixed a bug which could hide non-ok status in CompactionJob::Run()

Summary: Fixed a bug which could hide non-ok status in CompactionJob::Run()

Test Plan: make

Reviewers: sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D28995