Json ruby 2.2.0

Incompatibility json Gem with Ruby 2.2.0

rb_str_new expects 2 arguments

https://github.com/flori/json/issues/229

Gemfile

@@ -3,7 +3,7 @@ source "http://rubygems.org"
gem 'httparty'
gem 'childprocess', '0.3.6'
gem 'charlock_holmes', '0.6.9.4'
-gem 'json', '~> 1.7.7'
+gem 'json', :github => 'kgrz/json'
group :development do
gem 'coveralls', require: false