BREAKING CHANGE: HttpFactory is no longer available.
This factory provided a function alternative to the `request` method of the
Http class, but added no real value. The additional factory required an
additional IHttp interface, an odd way to inject while preserving type information
(`@Inject(HttpFactory) http:IHttp`), and required additional documentation in the
http module.
Closes#2564
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