Add starter-kit zip files to repo

These should be included so that anybody can build and update the docs
with as little confusion as possible.

I've left the directory in .gitignore so additions need to be
intentional as part of a release.
Do not automatically select other options

For <select multiple />, `value` is an array and should not be
converted to a string.
Fix a perf issue of <select multiple />

`indexOf` was used inside a loop. Use an object and
`hasOwnProperty` instead.