Fix tooltip viewport example

- Move example to correct location docs/examples/
- Move custom JS and CSS into stand-alone files
- Update headers and footers
- Copy-editing
Fix HTML errors
Add Gist & Customizer URLs to customized files & config.json

Fixes #9951
Fixes #12865
grunt dist
Merge pull request #13205 from twbs/fix-9951

Add Gist & Customizer URLs to customized files & config.json
Tweak JS style and the relevant JSHint and JSCS checks.
Comply to the new style.
Remove `laxbreak`.
Remove `boss`.
Enable `requireCurlyBraces`.
Enable `es3`.
Switch to using plain `if/else` statements when there's no assignment.

The minizer outputs the same code anyway, and this has better readability.
Minor whitespace changes.
Switch to `(function){..})()`.
More updates to the JSHint options.
Run `grunt`.