Bump version to 2.1.2

Yotta version bumped to 2.1.3, as we had to do one more patch release to the
yotta registry to accommodate for dependencies updates.
diff --git a/ChangeLog b/ChangeLog
index 4ae1a36..aa96b18 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,6 @@
 mbed TLS ChangeLog (Sorted per branch, date)
 
-= mbed TLS 2.1.2 released 2015-10-xx
+= mbed TLS 2.1.2 released 2015-10-06
 
 Security
    * Added fix for CVE-2015-5291 to prevent heap corruption due to buffer