Making use of the closure-util package

This provides some initial development utilities for people using Node.

Instructions for installing:

    npm install

After pulling down the dependencies, you can start a developement server that provides the libraries (ol and Closure Library) in debug mode (not minified/compiled).  Run the dev server with the following:

    npm start

Currently, the example index page needs to be built with `build.py`.  After building that, you should be able to browse all static files, view the examples and run the tests.
Don't use private `date_` property

It looks like at some point the Closure Library exposed a public `date` property for this same purpose.  The version of the Closure Library that comes with the closure-util package uses this property.  At some point later, I'll demonstrate how we can control which version of the library we depend on.
Test conventions

 * use `be` or `equal` for strict equality tests
 * use `be.a` for `instanceof` checks
 * use dot instead of bracket notation