Add the first Changelog

CHANGELOG.md

+# Changelog
+
+
+## 0.4 (unreleased)
+
+New:
+
+* Add console command for account creation 
+  [#1202](https://github.com/owncloud/mail/pull/1202) @ChristophWurst
+
+* Drop owncloud 7 support 
+  [#1267](https://github.com/owncloud/mail/pull/1267) @ChristophWurst
+
+* Address collector - Addresses of sent mails will be used for auto-completion
+  [#1276](https://github.com/owncloud/mail/pull/1276) @ChristophWurst
+
+Fixes:
+
+* 
+
+## 0.3.1 (unreleased)
+
+
+Fixes:
+
+* Message list is not hidden when adding a secondary account
+  [#1295](https://github.com/owncloud/mail/issues/1295) @Gomez
+
+* Sub-sub folders not handled correctly
+  [#618](https://github.com/owncloud/mail/issues/618) @ErikPel
+
+## 0.3 (2016-02-03)
+
+