Fix gemspec homepage to point to rails repo [ci skip]

Author: carlosantoniodasilva

sprockets-rails.gemspec

@@ -2,7 +2,7 @@ Gem::Specification.new do |s|
   s.name = "sprockets-rails"
   s.version = "2.0.0.rc1"
 
-  s.homepage = "https://github.com/josh/sprockets-rails"
+  s.homepage = "https://github.com/rails/sprockets-rails"
   s.summary  = "Sprockets Rails integration"
 
   s.files = Dir["README.md", "lib/**/*.rb"]