(BKR-147) add Gemfile setting for BEAKER_VERSION for puppet...

puppetdb, etc

- support for BEAKER_VERSION and BEAKER_RSPEC_VERSION in gemfile

Gemfile

@@ -21,11 +21,16 @@ group :development, :unit_tests do
 end
 
 beaker_version = ENV['BEAKER_VERSION']
+beaker_rspec_version = ENV['BEAKER_RSPEC_VERSION']
 group :system_tests do
   if beaker_version
     gem 'beaker', *location_for(beaker_version)
   end
+  if beaker_rspec_version
+    gem 'beaker-rspec', *location_for(beaker_rspec_version)
+  else
     gem 'beaker-rspec',  :require => false
+  end
   gem 'serverspec',    :require => false
 end