(PDOC-9) Update acceptance take task for Jenkins

In order to allow for multiple platforms on Jenkins, use the
platform environment variable in the rake task for acceptance tests
to determine which platform to run on.

Rakefile

@@ -20,5 +20,5 @@ end
 task :acceptance do
   sh "puppet module build"
   sh "puppet module build spec/unit/puppet/examples/test"
-  sh "rspec spec/acceptance/*.rb"
+  sh "BEAKER_set=#{ENV["platform"]} rspec spec/acceptance/*.rb"
 end

spec/acceptance/running_strings_yardoc.rb

@@ -20,9 +20,7 @@ describe 'Genearting module documation using yardoc action' do
   end
 
   it "should generate documenation for 3x functions" do
-    on master, 'cat /root/doc/Puppet3xFunctions.html' do
-      expect(read_file_on(master, '/root/doc/Puppet3xFunctions.html')).to have_tag('.docstring .discussion', :text => /documentation for `function3x`/)
-    end
+    expect(read_file_on(master, '/root/doc/Puppet3xFunctions.html')).to have_tag('.docstring .discussion', :text => /documentation for `function3x`/)
   end
 
   it "should generate documenation for 4x functions" do