Pin rspec gems

Gemfile

@@ -2,7 +2,8 @@ source ENV['GEM_SOURCE'] || "https://rubygems.org"
 
 group :development, :unit_tests do
   gem 'rake',                    :require => false
-  gem 'rspec-puppet',            :require => false
+  gem 'rspec-core', '3.1.7',     :require => false
+  gem 'rspec-puppet', '~> 1.0',  :require => false
   gem 'puppetlabs_spec_helper',  :require => false
   gem 'puppet-lint',             :require => false
   gem 'simplecov',               :require => false