fix(generator): remove invalid sort on elements

cacheUris are sorted later.  sorting the elements can be invalid (e.g.
SimpleStringLiteral has == but no compareTo)

Closes #554
docs(contributing): add developer docs explaining how to setup and run tests

- Create a first version of developer documentation explaining how to
setup and run AngularDart tests locally and on Travis.
- Update `CONTRIBUTING.md` to refer to this new doc.

Closes #322. Assumes #545.

Closes #548
feat(forms): provide support for reseting forms, fieldsets and models
chore(style): clean up indentation.
fix(ng-value): Add ng-value support for checked/radio/option

Closes# 543
fix(doc-gen): dartbug.com/16752
fix(ngModel): ensure validation occurs when the model value changes upon digest
feat(forms): generate ng-submit-valid / ng-submit-invalid CSS classes upon form submission