Add a crawler to make sure all links resolve and do not 404

[samccone]

xref https://github.com/marionettejs/backbone.marionette/issues/2211

[jasonLaster]

this is what I have in mind:

docs = File.read('docs/*.md');

links = docs.map do |doc|
   return doc.scan(/\[.*\]'(\S+\)/)
end

links.each do |link|
  resp = url.get(link)
  if !resp
    puts "bad link"
  end
end

apologize for the ruby

[samccone]

yep :) I think we can do this statically as a test ... should be quite simple actually