lock the json gem to a 1.9.3-friendly version

oreoshake · oreoshake · commit 951beee9cb37 · 2016-07-08T12:39:12.000-10:00
diff --git a/Gemfile b/Gemfile
@@ -5,6 +5,7 @@ gemspec
 group :test do
   gem "tins", "~> 1.6.0" # 1.7 requires ruby 2.0
   gem "pry-nav"
+  gem "json", "~> 1"
   gem "rack", "~> 1"
   gem "rspec"
   gem "coveralls"
