[KOE-96] Added XML escaping to OOF messages.

src/AcaciaZPushPlugin/AcaciaZPushPlugin/Utils/ActiveSync.cs

@@ -266,7 +266,7 @@ namespace Acacia.Utils
                                 s.Append("<Enabled>1</Enabled>");
                                 s.Append("<BodyType>Text</BodyType>");
                                 s.Append("<ReplyMessage>");
-                                s.Append(_value.Message[i].Message); // TODO: escaping
+                                s.Append(_value.Message[i].Message.EncodeXML());
                                 s.Append("</ReplyMessage>");
                             }
                         }

src/AcaciaZPushPlugin/AcaciaZPushPlugin/Utils/StringUtil.cs

@@ -77,6 +77,8 @@ namespace Acacia.Utils
 
         #endregion
 
+        #region XML
+
         public static string ToXMLString(this XmlNode xml)
         {
             using (var stringWriter = new StringWriter())
@@ -88,6 +90,13 @@ namespace Acacia.Utils
             }
         }
 
+        public static string EncodeXML(this string s)
+        {
+            return System.Security.SecurityElement.Escape(s);
+        }
+
+        #endregion
+
 
         #region Resources