Incorrect dependencies for logstash-output-elasticsearch-license

Hi,

The plugin 'logstash-output-elasticsearch-license' fails to install because it has twiddle-wakka for an old version of 'logstash-output-elasticsearch'.

From https://rubygems.org/gems/logstash-output-elasticsearch-license/versions/0.0.1:

RUNTIME DEPENDENCIES:
logstash-output-elasticsearch ~> 0.2

But I have the latest version of 'logstash-output-elasticsearch' installed: 2.6.1 which results in bundler errors.

Are the plugins really not compatible (which I'd find odd since it's just a simple addition to support the license) or is it just in need of a dependency update?

Thanks!