- adds `render_xls` to `DateWidget`
- adds `format` parameter to `with_widget` to invoke specific widget renderer
Merge pull request #16 from mrc75/feature/xls-formats

fixes Date format on excel reports
bump 0.3
Merge branch 'release/0.3' into develop

* release/0.3:
  bump 0.3
bump 0.3.1
Merge branch 'release/0.3.1' into develop

* release/0.3.1:
  bump 0.3.1