Worker readme

* Add common info
* Add creating worker block
* Add block about task queuing
* Add block about task scheduling
Guys do you want to run .go code(using 1.1 compiler) or compiled binary?
https://github.com/iron-io/iron_worker_ruby_ng/blob/master/lib/iron_worker_ng/code/runtime/go.rb

I would recommend to compile on local env and upload binary.