Make abstractions in Util more ruby-friendly

[ffloyd]

The problem

Right now modules under Flows::Util work like "module patchers":

module YourModule
  SomeStuffFromUtils.call(self, opts)
end

I see this code as a very confusing one for an average Ruby developer.

The solution

In my opinion, the more ruby-friendly and less confusing way will be "module factory":

MyBehaviour = SomeStuffFromUtil.make_module(opts)

module YourModule
  extend MyBehaviour
end

Also, more condensed way of usage is possible:

module YourModule
  extend SomeStuffFromUtil.make_module(opts)
end

But in this way, you'll have an anonymous module which can be inconvenient for backtrace readers and YARD documentation tool.

And it will be convenient if an error will be raised if you're including generated module instead of extending and vise versa.