Add style guides to help controllers creation

[felipefontoura]

Good job, but Victor many other topics need to be defined too:

• Naming.
• Restfully controllers as possible.
• Use of callbacks for a clean code.
• Use respond_with for a clean code.
• Use of callbacks and build method or nested controllers/collections.
• Flash messages and responder gem.
• And of course params require: params.require(:account_center).permit(:name, :kind, ...)

And write an example too, like Ruby style-guide. I think you can copy and paste from our project but changing name and subject.

Thanks :+1:

[felipefontoura]

@vgsantoniazzi I suggested follow indentation level.

I think for first version this guide is very good!

:headphones:

[felipefontoura]

:pizza: