fix package.json, make npm-installable

Hi there!

I tried to install/use this repo via npm, but with no success:

```
❯ npm install --save JohnAlbin/normalize-scss
npm ERR! Darwin 13.4.0
npm ERR! argv "node" "/usr/local/bin/npm" "install" "--save" "JohnAlbin/normalize-scss"
npm ERR! node v0.10.33
npm ERR! npm  v2.1.7
npm ERR! file /var/folders/cj/wr9t2cks6lldpxshyxmdj3gc0000gn/T/npm-67164-df0f40a8/unpack-e18b70295f95/package.json
npm ERR! code EJSONPARSE

npm ERR! Failed to parse json
...
```

Just a simple JSON-error (trailing comma) I fixed in the pull request.

(For more information:
I am trying to move away from bower using just npm — just to give that a try...
see https://github.com/bower/bower/issues/1520 and http://blog.npmjs.org/post/101775448305/npm-and-front-end-packaging)