Merge pull request #62 from mashhurs/remove-ls-version-limit

Remove Logstash version limiting.

Feat: ECS compatibility (added headers_target and attachments_target) (…

…#55)

Bump to v.3.1.0 (#51)

Bumps version to publish changes from #48
Reorders options table in documentation

[skip ci] Travis: switch to openjdk8

set default_codec doc attribute

[skip ci] update gemspec summary

Version bump

For elastic/logstash#7993

[ci skip]

bump patch level for doc generation

dependency logstash-core-plugin-api >= 1.60 <= 2.99

Make sure all the gems were published under jruby