BREAKING CHANGES:
Dart applications and TypeScript applications meant to transpile to Dart must now
import `package:angular2/bootstrap.dart` instead of `package:angular2/angular2.dart`
in their bootstrap code. `package:angular2/angular2.dart` no longer export the
bootstrap function. The transformer rewrites imports of `bootstrap.dart` and calls
to `bootstrap` to `bootstrap_static.dart` and `bootstrapStatic` respectively.
The BaseRequestOptions class is responsible for declaring default values,
while the RequestOptions class is merely responsible for setting values
based on values provided in the constructor.
This implementation only works in JavaScript, while the Observable transpilation
story gets worked out. Right now, the service just makes a simple request,
and returns an Observable of Response.
Additional functionality will be captured in separate issues.
Fixes#2028
