```ruby
# -*- encoding: utf-8 -*-
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'hubdown/version'

Gem::Specification.new do |gem|
  gem.name          = "hubdown"
  gem.version       = Hubdown::VERSION
  gem.authors       = ["jsk"]
  gem.email         = ["knomedia@gmail.com"]
  gem.description   = %q{CLI for GitHub Flavored markdown to html convervsion}
  gem.summary       = %q{CLI for GitHub Flavored markdown to html conversion}
  gem.homepage      = "https://github.com/knomedia/hubdown"
  
  gem.add_dependency 'github-markdown'
  gem.add_dependency 'mixlib-cli'
  gem.add_dependency 'nokogiri'

  gem.files         = `git ls-files`.split($/)
  gem.executables   = gem.files.grep(%r{^bin/}).map{ |f| File.basename(f) }
  gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
  gem.require_paths = ["lib"]
end
```

Add dependent gem version numbers
user
```ruby
# -*- encoding: utf-8 -*-
lib = File.expand_path('../lib', __FILE__)
$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
require 'hubdown/version'

Gem::Specification.new do |gem|
  gem.name          = "hubdown"
  gem.version       = Hubdown::VERSION
  gem.authors       = ["jsk"]
  gem.email         = ["knomedia@gmail.com"]
  gem.description   = %q{CLI for GitHub Flavored markdown to html convervsion}
  gem.summary       = %q{CLI for GitHub Flavored markdown to html conversion}
  gem.homepage      = "https://github.com/knomedia/hubdown"
  
  gem.add_dependency('github-markdown', '>=0.5.3')
  gem.add_dependency('mixlib-cli', '>=1.2.2')
  gem.add_dependency('nokogiri', '>=1.5.6')

  gem.files         = `git ls-files`.split($/)
  gem.executables   = gem.files.grep(%r{^bin/}).map{ |f| File.basename(f) }
  gem.test_files    = gem.files.grep(%r{^(test|spec|features)/})
  gem.require_paths = ["lib"]
end
```
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