Prepare changelog for v1.0.4

Author: dbkr

CHANGELOG.md

@@ -1,3 +1,9 @@
+Changes in [1.0.4](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v1.0.4) (2019-03-18)
+===================================================================================================
+[Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v1.0.4-rc.1...v1.0.4)
+
+ * No changes since rc.1
+
 Changes in [1.0.4-rc.1](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v1.0.4-rc.1) (2019-03-13)
 =============================================================================================================
 [Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v1.0.3...v1.0.4-rc.1)