feat(mock): support for JSON in HttpBackend

Closes #236
fix(scope): honor $skipAutoDigest on non-root scopes

Close #391
fix(docs): correct typo
chore(contributing): added contributing instructions.
chore(contributing): fix typo
docs(Scope): complete missing documentation for scope methods/properties

Closes #287
chore(test): fix analyze casting issues on ng_model_spec.dart
feat(forms): provide support for controls and state flags
feat(forms): add support for validation handling for multiple error types
feat(forms): provide support for parent form communication
feat(ngModel): provide support for custom validation handlers
feat(core): provide support to define the same selector on multiple directives
chore(docs): add docs for NgForm, NgModel and each of the NgModel validators
docs(readme): add @AngularDart and travis badge
chore(todo demo): Update the directory structure to be compatible with 'pub serve'
feat(js size): Add a default @MirrorsUsed to Angular.

Closes #409, #237
docs(mirrors): Update comments about MirrorsUsed
feat(helloworld): MirrorsUsed
fix(generator): Avoid compile-time filter map querying when generating static parser.

This fixes https://github.com/angular/angular.dart/issues/432.

Also consistenly load libraries through the package root to avoid getting in
trouble if the same library is loaded through different URIs.
fix(expression_extractor): implemented support for wildcard attr selector

Fixes #447