Replace stringTrimRegex with a shorter and faster variant:

1) Don't use unnecessary captures.
2) Use character classes instead of alternations.
3) Replace \u00a0 with \xa0 (saves 4 bytes).

According to http://jsperf.com/char-class-vs-alt this is 55% faster in IE7, 61% faster in Chrome 19, and a whopping 1840% faster in Firefox 11.
stringTrim: Incorporate Michael Best's improvements on #611 (uses native String.prototype.trim if available).
fixes #733
update version.txt to 2.2.1
.travis.yml uses npm package
added npm-debug.log to .gitignore
add package.json and .npmignore
update README
better handling of some cases
add bugs field in package.json
Tweak text in README and package.json
Avoid duplication of version number by pulling it from package.json
For the NPM module, use only the debug build (just because it would be very weird to reference minified sources in a Node project)
Stop using npm's "scripts" feature because it doesn't seem to work on Windows (tries to run the scripts in a regular cmd session instead of Git Bash)
Change .npmignore to use opt-in instead of out-out, to avoid duplicating contents of .gitignore
re-add scripts section in package.json with fixes to run in Windows shell
use more common location of "find" to fix travis build
alter travis config so it doesn't build Knockout twice; alter build script so that failed tests exit the script properly
Add checkedValue binding that works with the checked binding to allow for arbitrary values for checkboxes and radio buttons.
Add spec about behavior of radio buttons with an observable checkedValue, even though I think that the behavior should be different.