Updates changelog to include recent changes in the upcoming release

CHANGELOG

@@ -1,2 +1,14 @@
-v 0.4.0
+v0.4.0
   - First open-source version of DENSEanalysis
+
+v0.5.0
+  - Support for versions of MATLAB >= R2012b. Support for 2009b - 2012a has
+    been removed.
+  - Adds plugin framework for easy user customization of the interface and
+    incorporation of custom post-processing
+  - Automatic checking for new versions of the DENSEanalysis software
+  - Improvements to the DENSEdata interface to allow easier interaction
+    with underlying data
+  - Adds keyboard shortcuts to improve productivity: copy, paste, undo, etc.
+  - Bundles some unit tests with the application to ensure minimal
+    functionality