* 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.
- Dart code: fix issues raised by @thso during review.
- Dart code: remove "show x" clauses from imports.
- Dart add docsync config file.
- Prose: make consistent use of _Http variables; otherwise use "HTTP".
- Prose: add links to the demos list.
* _heroesUrl as static const
New Dart prose, update Dart and Ts code
+ guide/server-communication/ts: update to docs and example code
+ guide/server-communication/dart: new prose, update example code
+ ignore all npm-debug.logs
+ make Jade ul li TOC elements more compact.