* plunker builder removes files and scripts not needed in plunkers (e.g., systemjs.config.js)
* no longer adds placeholder README.md (deemed a distraction)
* tag is now "Angular" instead of "Angular2"
* new plnkr.json "includeSystemConfig" option adds systemjs.config.js back; needed for testing plnkrs.
* incidentally changes comment "Polyfill(s)" to "Polyfills" in all index.html
Misc fixes to problems with the tutorial examples, as detected by the new e2e tests. Now the toh-4 index.html is identical to those of the previous parts.
Fixes#1609.
Ward Bell
Jesús Rodríguez
Patrice Chalin