Update changelog

CHANGES

 Change History
 ==============
 
+1.4 (unreleased)
+----------------
+
+This version comes with a change in the SQL tables format, to fix a potential
+crash of storage nodes when storing values that only differ by the compression
+flag. See UPGRADE notes if you think your application may be affected by this
+bug.
+
+- Performance and features:
+
+  - 'Importer' storage backend has been significantly sped up.
+
+  - Support for TokuDB has been added to MySQL storage backend. The engine is
+    still InnoDB by default, and it can be selected via a new 'neostorage'
+    option.
+
+  - A 'neomaster' option has been added to automatically start a new cluster
+    if the number of pending storage nodes is greater than or equal to the
+    specified value.
+
+- Bugfixes:
+
+  - Storage crashed when reading empty transactions. We still need to decide
+    whether NEO should:
+
+    - continue to store such transactions;
+    - ignore them on commit, like other ZODB implementation;
+    - or fail on commit.
+
+  - Storage crashed when a client tries to "steal" the UUID of another client.
+
+  - Client could get stuck forever on unreadable cells when not connected to the
+    master.
+
+- Plus fixes and improvements to logging and debugging.
+
 1.3 (2015-01-13)
 ----------------