Remove core JSON rendering

[Ortuna]

Just to come full circle with the whole JSON rendering feature(from #1044). I believe the auto rendering to JSON in rendering.rb should be removed.

This should allow for:

• Removing the expensive JSON gems(not sure if we can, but seems like we can. Nothing else is using it).
• Leverage sinatra-contrib for any JSON rendering.

This does break 2 tests, and would be a breaking change.
Tests break here and here

What is proposed:

• Remove multi_json gem from support_lite.rb
• Remove conditional in rendering.rb
• Remove tests here and here
• Add documentation to padrino-docs to show use of sinatra-contrib and rendering JSON.

I can submit code for these changes but I'm not familiar with the procedures for "breaking" changes in Padrino.

Appreciate your time, thanks for the hard work on Padrino!

[ujifgc]

I think this is a good initiative. Json usage is something which should be stipulated on design phase of developing an application, not something you jump to use half way. Interface related gems should not hang there just in case. It might be needed for some UI-heavy gems like padrino-admin, but not padrino-core.

[achiurizo]

👍 what do you guys think @padrino/core-members ?

[DAddYE]

Yea I agree!

[nesquena]

Yes, I agree I don't think JSON needs to be baked. Breaking changes are OK but obviously we like to avoid them where we can. In this case, I don't think the negative fallout will be very high for removing this.

[Ortuna]

Thanks all, this was merged.

[nesquena]

Thank you. Appreciate the recent patches.

[postmodern]

The downside of this, is that sinatra-contrib pulls in many other dependencies (namely eventmachine), just for a method as simple as:

def json(object)
  content_type :json
  object.to_json
end