Added XML header to the samples

docs/samples/sync_request.xml

@@ -1,24 +1,25 b''
+<?xml version="1.1" encoding="UTF-8" ?>
 <request>
     <version>
         <protocol>1</protocol>
         <models>
             <post>1</post>
         </models>
     </version>
     <data>
         <type>sync</type>
         <timestamp>0</timestamp>
         <hosts>
             <allow>
                 <host>*</host>
             </allow>
             <deny></deny>
             <pools>
                 <pool>test1</pool>
                 <pool>test2</pool>
             </pools>
         </hosts>
         <!-- Get only posts id to load posts later (maybe from several hosts) -->
         <id-only>true</id-only>
     </data>
 </request>

docs/samples/sync_response.xml

@@ -1,22 +1,23 b''
+<?xml version="1.1" encoding="UTF-8" ?>
 <response>
     <status>success</status>
     <posts>
         <post>
             <id>id1/1</id>
             <title>13</title>
             <text>Thirteen</text>
             <thread>id1/12</thread>
             <pub-time>12</pub-time>
             <edit-time>13</edit-time>
         </post>
         <post>
             <id>id1/2</id>
         </post>
         <post>
             <id>id2/1</id>
         </post>
         <post>
             <id>id2/5</id>
         </post>
     </posts>
 </response>