feat(angular.bootstrap): support deferred bootstrap

This features enables tools like Batarang and test runners to
hook into angular's bootstrap process and sneak in more modules
into the DI registry which can replace or augment DI services for
the purpose of instrumentation or mocking out heavy dependencies.

If window.name contains prefix NG_DEFER_BOOTSTRAP! when
angular.bootstrap is called, the bootstrap process will be paused
until angular.resumeBootstrap is called.

angular.resumeBootstrap takes an optional array of modules that
should be added to the original list of modules that the app was
about to be bootstrapped with.