improved required/recommended attributes

[mpapis]

according to http://guides.rubygems.org/specification-reference/#description description is not required - removed annoying warning

[mpapis]

also moved email and hompage to recommended so the docs at http://guides.rubygems.org/specification-reference/ match https://github.com/rubygems/rubygems/pull/1046/files#diff-05477d38d75c98664b0e7dec6eb73b45L2604:

%w[author email homepage summary].each do |attribute|
  value = self.send attribute
  warning "no #{attribute} specified" if value.nil? or value.empty?
end

(yes the docs will require refresh)

[drbrain]

I can't remember if the warning or the documentation came first, did you check? I'd rather resolve this based on history than deferring to the documentation.

[mpapis]

actually I based it on my experience with rubygems ;) requiring both description + summary and not allowing them to be the same is just pointless, I either get missing or duplicate warning, and it's true for all my gems, I do not have a big description, usually the single line summary tells basic story and more detailed explanation might take pages in README.md