Update changelog

CHANGES.md

+0.2 (2014-04-09)
+================
+
+ * Major overhaul of the web server:
+   + changes in configuration items
+   + cleaner isolation between elections
+   + add per-site and per-election administration pages
+   + elections imported from the configuration file must be explicitly
+     listed (no more directory scanning)
+   + authentication is more modular
+   + changes in CAS authentication method:
+     - invoke credential requestor with `renew=true`
+     - do not assume CAS paths start with `/cas/`
+   + change in the password authentication method:
+     - the password file must be uploaded via the web server (no more
+       reading on-disk file) before the method is used for the first
+       time
+   + automatic logout after successful ballot casting
+   + online creation of election
+ * Remove hardcoded default group
+
 0.1.1 (2014-02-13)
 ==================