message: Added html-to-ppt rowspan fix
diff: # Change Log
  -## [v2.1.0](https://github.com/gitbrent/pptxgenjs/tree/v2.1.0) (2018-03-??)
  +## [v2.1.0](https://github.com/gitbrent/pptxgenjs/tree/v2.1.0) (2018-04-??)
  [Full Changelog](https://github.com/gitbrent/pptxgenjs/compare/v2.0.0...v2.1.0)
  **Fixed Bugs:**
  - HTML-to-PowerPoint is creating many extra columns with colspan [\#284](https://github.com/gitbrent/PptxGenJS/issues/284) ([svaak](https://github.com/svaak))
  +- HTML-to-PowerPoint rowspan is not working ([gitbrent](https://github.com/gitbrent))
  **Implemented Enhancements:**
  