* update to beta.22
* Dart SDK 1.19.0 or later is required
* minor edits to sample app titles to e2e tests pass
* Renamed “Angular 2” to “Angular” so that shared e2e tests pass.
* Tweak to QS prose.
- Renamed `angular2_getting_started` to `angular2_quickstart` (to match
TS).
- s/-/_/g in project names elsewhere (only toh-5 & -6 needed to be
updated).
Fixes#378.
Yang Lin
Patrice Chalin
Patrice Chalin