Checking in changes prior to tagging version "0.2.2".

Changelog diff:

diff --git a/History.md b/History.md
index 05ed56b..03abbbb 100644
--- a/History.md
+++ b/History.md
@@ -1,3 +1,10 @@
+# Revision history for murmurhash3
+
+0.2.2 / 2013-06-01
+==================
+
+  * Update document
+
 0.2.1 / 2013-04-04
 ==================