set default_codec doc attribute

[skip ci] update gemspec summary

version bump for some docs fixes

bump patch level for doc generation

Update plugin to the new event api (#13)

Update logstash-input-wmi.gemspec

dependency logstash-core-plugin-api ~> 1.0

dependency logstash-core >= 2.0.0.beta2 < 3.0.0

dependency logstash-core >= 2.0.0.snapshot < 3.0.0

bump version