message: Prepare changelog for v0.8.7-rc.2
diff: +Changes in [0.8.7-rc.2](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v0.8.7-rc.2) (2017-04-10)
  +=============================================================================================================
  +[Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v0.8.7-rc.1...v0.8.7-rc.2)
  +
  + * fix the warning shown to users about needing to export e2e keys
  + [\#797](https://github.com/matrix-org/matrix-react-sdk/pull/797)
  +
  Changes in [0.8.7-rc.1](https://github.com/matrix-org/matrix-react-sdk/releases/tag/v0.8.7-rc.1) (2017-04-07)
  =============================================================================================================
  [Full Changelog](https://github.com/matrix-org/matrix-react-sdk/compare/v0.8.6...v0.8.7-rc.1)
  