Fix TravisCI for Ruby < 2

Author: ghoneycutt

Gemfile

@@ -18,7 +18,12 @@ else
 end
 
 if RUBY_VERSION >= '1.8.7' and RUBY_VERSION < '2.0'
-  gem 'json', '~> 1.0'
+  # json 2.x requires ruby 2.0. Lock to 1.8
+  gem 'json', '~> 1.8'
+  # json_pure 2.0.2 requires ruby 2.0. Lock to 2.0.1
+  gem 'json_pure', '= 2.0.1'
+else
+  gem 'json'
 end
 
 if facterversion = ENV['FACTER_GEM_VERSION']