Allow for installing plugins

[spuder]

Feature request - Allow cookbook to install kibana plugins.

Most specifically, the timelion plugin

./bin/kibana plugin -i kibana/timelion
service kibana restart

https://www.elastic.co/blog/timelion-timeline

Plugins do not persist across kibana upgrades.

[martinb3]

I'd love to review/merge this feature. Please consider a PR! 👍

[davidski]

Challenge....accepted! PR #114 submitted. Please be critical in reviewing. I don't have a lot of experience with resource authoring.

[martinb3]

Awesome @davidski! I saw you were going to rebase, so I'll hold off on comments until you ping me there saying you're ready :)

[davidski]

Thanks, @martinb3! Resubmitted under #115 . Appreciate the time!