2.4.0 release

Fixes elastic#5842

fix. add vendor files to logstash-core gem

Fixes elastic#5838

Migrate Logstash to Log4j2 Logging (elastic#5651)

Migrate to use Log4j2 for Logstash logging

Add relnoltes for alpha5

Fixes elastic#5742

Release 2.3.4 (elastic#5599)

Release 5.0.0-alpha4 (elastic#5564)

Revert geoip filter to 2.x (elastic#5502)

Add changelog for 5.0.0-alpha3 (elastic#5396)

* Add changelog for 5.0.0-alpha3

Release 5.0.0-alpha3 snapshot4

5.0.0.alpha3.snapshot1