Remove gem build warnings

Author: michael-misshore

critical-path-css-rails.gemspec

@@ -9,12 +9,13 @@ Gem::Specification.new do |gem|
   gem.summary     = 'Critical Path CSS for Rails!'
   gem.description = 'Only load the CSS you need for the initial viewport in Rails!'
   gem.license     = 'MIT'
+  gem.homepage    = 'https://rubygems.org/gems/critical-path-css-rails'
 
   gem.files        = `git ls-files`.split("\n")
   gem.executables  = `git ls-files -- bin/*`.split("\n").map { |f| File.basename(f) }
   gem.require_path = 'lib'
 
-  gem.add_development_dependency 'combustion', '~> 1.1.0'
+  gem.add_development_dependency 'combustion', '~> 1.1', '>= 1.1.0'
 
   gem.extensions = ['ext/npm/extconf.rb']
 end