Add shared gem path for Puppetserver >= 5.3

Since 5.3.0 Puppet Server can use some gems shipped by puppet-agent. For
this the gem-path settings of puppetserver.conf needs to be extend by
/opt/puppetlabs/puppet/lib/ruby/vendor_gems. This is the default as
shipped by Puppetlabs.

Fixes theforemanGH-630.

spec/classes/puppet_server_puppetserver_spec.rb

@@ -830,6 +830,34 @@
         end
       end
 
+      describe 'gem-path' do
+        context 'when server_puppetserver_version > 2.7 but < 5.3' do
+          let(:params) do
+            default_params.merge(
+              :server_puppetserver_version => '5.0.0',
+            )
+          end
+
+          it 'should have gem-path: [${jruby-puppet.gem-home}, "/opt/puppetlabs/server/data/puppetserver/vendored-jruby-gems"] in config' do
+            content = catalogue.resource('file', '/etc/custom/puppetserver/conf.d/puppetserver.conf').send(:parameters)[:content]
+            expect(content).to include(%Q[    gem-path: [${jruby-puppet.gem-home}, "/opt/puppetlabs/server/data/puppetserver/vendored-jruby-gems"]\n])
+          end
+        end
+
+        context 'when server_puppetserver_version >= 5.3' do
+          let(:params) do
+            default_params.merge(
+              :server_puppetserver_version => '5.3.0',
+            )
+          end
+
+          it 'should have gem-path: [${jruby-puppet.gem-home}, "/opt/puppetlabs/server/data/puppetserver/vendored-jruby-gems", "/opt/puppetlabs/puppet/lib/ruby/vendor_gems"] in config' do
+            content = catalogue.resource('file', '/etc/custom/puppetserver/conf.d/puppetserver.conf').send(:parameters)[:content]
+            expect(content).to include(%Q[    gem-path: [${jruby-puppet.gem-home}, "/opt/puppetlabs/server/data/puppetserver/vendored-jruby-gems", "/opt/puppetlabs/puppet/lib/ruby/vendor_gems"]\n])
+          end
+        end
+      end
+
       describe 'when server_puppetserver_version < 2.2' do
         let(:params) do
           default_params.merge(:server_puppetserver_version => '2.1.0')

templates/server/puppetserver/conf.d/puppetserver.conf.erb

@@ -16,7 +16,11 @@ jruby-puppet: {
     # This setting defines the complete "GEM_PATH" for jruby.  If set, it should include
     # the gem-home directory as well as any other directories that gems can be loaded
     # from (including the vendored gems directory for gems that ship with puppetserver)
+<%- if scope.function_versioncmp([@server_puppetserver_version, '5.3']) >= 0 -%>
+    gem-path: [${jruby-puppet.gem-home}, "<%= @server_puppetserver_vardir %>/vendored-jruby-gems", "/opt/puppetlabs/puppet/lib/ruby/vendor_gems"]
+<% else -%>
     gem-path: [${jruby-puppet.gem-home}, "<%= @server_puppetserver_vardir %>/vendored-jruby-gems"]
+<%- end -%>
 
 <%- end -%>
     # PLEASE NOTE: Use caution when modifying the below settings. Modifying