Prepare changelog for v0.10.3

Author: dbkr

CHANGELOG.md

@@ -1,3 +1,9 @@
+Changes in [0.10.3](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v0.10.3) (2017-09-06)
+=====================================================================================================
+[Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v0.10.3-rc.2...v0.10.3)
+
+ * No changes
+
 Changes in [0.10.3-rc.2](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v0.10.3-rc.2) (2017-09-05)
 ===============================================================================================================
 [Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v0.10.3-rc.1...v0.10.3-rc.2)