Tests: Fix randomizedtest fail

Closes #49
Update to Lucene 4.10.2

Closes #50
update documentation with release 2.4.1
upgrade to lucene 5 snapshot
Upgrade to Lucene 5.0.0-snapshot-1637347
Upgrade to Lucene 5.0.0-snapshot-1641343
Add "ja_stop" filter

 * can use a predefined "_japanese_" stop words
 * can not use other predefined stop words

Closes #45
Add "ja_stop" filter

 * can use a predefined "_japanese_" stop words
 * can not use other predefined stop words
 * upgrade to lucene 5
 * add ja_stop to README

  Closes #45