message: Prepare changelog for v0.12.5
diff: +Changes in [0.12.5](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v0.12.5) (2018-05-17)
  +=====================================================================================================
  +[Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v0.12.4...v0.12.5)
  +
  + * Fix image size jumping regression
  + [\#1909](https://github.com/matrix-org/matrix-react-sdk/pull/1909)
  +
  Changes in [0.12.4](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v0.12.4) (2018-05-16)
  =====================================================================================================
  [Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v0.12.4-rc.6...v0.12.4)
  