Merge package.json, self-initialize objects, links in README branches.

This pull request adds a package.json, makes the behavior tree components self instantiate if called without new, and adds links in the README.

It demonstrates canonical form require() (versus relative) in copy of the initial test, now called `test_behavior_tree_2.js`. There is an [alternative branch `master-one-test`](https://github.com/rektide/bSn/tree/master-one-test) which overrides the completely valid, solid, relatively-pathed existing tests with this alternative form, rather than making a new file.

There are feature branches for all changes. This is by design: the code is great as is, and I'm not sure you necessarily want to pull in all these changes that I happen to favor.

`npm install` `npm test` will pull down nodeunit and run the tests, c/o the package.json file.