modify DirectoryCopier

[hn5092]

in the Stage2KerberosDirectoryCopyMapper ,we are skip hiddenFile,so,when we begin stage3 , we first compare src adn dst file number size by every dir , if this equalDirs use empty hiddenfilefilter, it must be false, so add hiddenFileFilter

[hn5092]

here is our log!
INFO [main] com.airbnb.reair.common.FsUtils: Number of files in hdfs://pajkcluster/user/hive/warehouse/jkgj_log.db/track_raw_wap211_log/pt=2016010600 (9) and hdfs://bxpajkcluster/user/hive/warehouse/jkgj_log.db/track_raw_wap211_log/pt=2016010600 (8) do not match!

[plypaul]

The DirectoryCopier is used by the incremental replication process too, so the filter may be better passed an argument to the function call.

[hn5092]

OK.i recommit for a later