Update CHANGELOG.md

Remove comments causing docgen issues and make a few edits

Fixes logstash-plugins#37

Update plugin api

 - Breaking: Updated plugin to use new Java Event APIs
 - relax logstash-core-plugin-api constrains
 - update .travis.yml

dependency logstash-core-plugin-api ~> 1.0

update version, changelog and contributors

dependency logstash-core >= 2.0.0.beta2 < 3.0.0

dependency logstash-core >= 2.0.0.snapshot < 3.0.0

move the mongo require out of the register method

Fixes logstash-plugins#14

bump version

Remove traces and references the meta logstash gem and change it to u…

…se the new logstash-core gem.