prepare 2.2.0 release

Author: bodewig

RELEASE_NOTES.md

@@ -1,6 +1,6 @@
 # Release Notes
 
-## XMLUnit.NET 2.2.0 - /Not Released, yet/
+## XMLUnit.NET 2.2.0 - /Released 2016-06-04/
 
 * `Input.FromByteArray` and `Input.FromString` now return `ISource`s
   that can be used multiple times.

src/doc/monodoc/core/index.xml

@@ -45,5 +45,5 @@
       under <format type="text/html"><a href="https://github.com/xmlunit/xmlunit.net/blob/master/LICENSE">the
       Apache License, Version 2.0</a></format>.</para></Remarks>
   <Copyright></Copyright>
-  <Title>XMLUnit.NET 2.2.0-alpha-01</Title>
+  <Title>XMLUnit.NET 2.2.0</Title>
 </Overview>

src/shared/CommonAssemblyInfo.cs

@@ -26,7 +26,7 @@ namespace Org.XmlUnit
     internal static class XmlUnitVersion
     {
         internal const string ApiVersion = "2.2.0";
-        internal const string AssemblyVersion = ApiVersion + ".84";
-        internal const string Version = ApiVersion + "-alpha-01";
+        internal const string AssemblyVersion = ApiVersion + ".90";
+        internal const string Version = ApiVersion + "";
     } 
 }