[Gemfile] Use https

Gemfile

@@ -6,7 +6,7 @@ def cp_gem(name, repo_name, branch = 'master')
   gem name, :git => url, :branch => branch
 end
 
-source 'http://rubygems.org'
+source 'https://rubygems.org'
 
 gemspec
 

Gemfile.lock

@@ -81,7 +81,7 @@ PATH
       xcodeproj (~> 0.23.1)
 
 GEM
-  remote: http://rubygems.org/
+  remote: https://rubygems.org/
   specs:
     activesupport (4.2.1)
       i18n (~> 0.7)