Basic domain check command implementation

app/views/epp/domains/check.xml.builder

@@ -1,3 +1,17 @@
 xml.epp_head do
-  xml.bla
+  xml.response do
+    xml.result('code' => '1000') do
+      xml.msg 'Command completed successfully'
+    end
+
+    xml.resData do
+      xml.tag!('domain:chkData', 'xmlns:domain' => 'http://www.nic.cz/xml/epp/domain-1.4', 'xsi:schemaLocation' => 'http://www.nic.cz/xml/epp/domain-1.4 domain-1.4.xsd') do
+        xml.tag!('domain:cd') do
+          xml.tag!('domain:name', @domain, 'avail' => 1)
+        end
+      end
+    end
+
+    xml << render('/epp/shared/trID')
+  end
 end

app/views/epp/shared/_trID.xml.builder

@@ -0,0 +1,4 @@
+xml.trID do
+  xml.clTRID params[:clTRID]
+  xml.svTRID @svTRID
+end