Remove unused third-party dependencies

[montlebalm]

We should remove any third-party dependencies that aren't being used. Here's what I've identified so far:

• jquery.min.js since we're already minifying code.
• json2.js, json3.js, json3.min.js since we're targeting browsers with native JSON classes.
• require.min.js should be moved outside the source directory since it isn't used in compilation.

Did I miss anything? Do we need to keep any of the above?

[brianbaker]

We might want to remove the blurb about unofficially supporting IE7 if we are going to remove the JSON lib.

[markhealey]

Even better — provide docs for building an IE 7-compatible version.

[montlebalm]

Resolved by #207.