feat(platform-server): support @angular/http from @angular/platform-server

This change installs HttpModule with ServerModule, and overrides bindings to
service Http requests made from the server with the 'xhr2' NPM package.

Outgoing requests are wrapped in a Zone macro-task, so they will be tracked
within the Angular zone and cause the isStable API to show 'false' until they
return. This is essential for Universal support of server-side HTTP.

scripts/ci-lite/offline_compiler_test.sh

@@ -3,7 +3,7 @@ set -ex -o pipefail
 
 # These ones can be `npm link`ed for fast development
 LINKABLE_PKGS=(
-  $(pwd)/dist/packages-dist/{common,forms,core,compiler,compiler-cli,platform-{browser,server},platform-browser-dynamic,router}
+  $(pwd)/dist/packages-dist/{common,forms,core,compiler,compiler-cli,platform-{browser,server},platform-browser-dynamic,router,http}
   $(pwd)/dist/tools/@angular/tsc-wrapped
 )