message: updated changelog for 3.3
diff: +## 3.3.0 August 12, 2017
  +
  +- implemented `Pass.transitType()` to set/get transit type for board passes (with values validation and constants)
  +- `Temlate` now loads/stores structure level values and passes them to Passes
  +
  ## 3.1.0 August 9, 2017
  - Added `Template.load` static method to load template, images and key from a folder (no localization support yet, but coming)
  