message: Updating changelog for upcoming Release 1.2.0
diff: # Change Log
  -## [v1.2.0](https://github.com/gitbrent/pptxgenjs/tree/v1.2.0) (2017-02-04)
  +## [v1.2.0](https://github.com/gitbrent/pptxgenjs/tree/v1.2.0) (2017-02-13)
  [Full Changelog](https://github.com/gitbrent/pptxgenjs/compare/v1.1.6...v1.2.0)
  **Implemented Enhancements:**
  - Allow custom Layout sizes (ex: A3) [\#29](https://github.com/gitbrent/PptxGenJS/issues/29) ([itskun](https://github.com/itskun))
  - Table cell marginPt should allow zero and take TRBL array [\#32](https://github.com/gitbrent/PptxGenJS/issues/32) ([ellisgl](https://github.com/ellisgl))
  - Formatting rules do not apply to string with '\n' in `addText()` [\#34](https://github.com/gitbrent/PptxGenJS/issues/34) ([itskun](https://github.com/itskun))
  +- Node module appends to last generated PPT on `save()` [\#38](https://github.com/gitbrent/PptxGenJS/issues/38) ([alexanderpepper](https://github.com/alexanderpepper))
  ## [v1.1.6](https://github.com/gitbrent/pptxgenjs/tree/v1.1.6) (2017-01-19)
  [Full Changelog](https://github.com/gitbrent/pptxgenjs/compare/v1.1.5...v1.1.6)
  