Initial attempt to create Gem file for plugin

I've created initial implementation `GEM` for plugin.
Tested gem usage only locally without publishing to `RubyGems` site.
Pleae consider that implementaiton is incomplete, so waiting for your feedback.

Couple of notes

* not sure what is `default_config.yml` is used for, so deleted it
* your email is not set in `gemspec` file
* installation docs are not yet updated
* not sure if dependencies are required in `gemspec`