* closes#3086
* samples reworked to conform to our sample style, make more sense, and cover the points in prose.
* copy edits to bring closer to Google docs standards.
* 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
