Supports package manager such as browserify, cortex, etc

Phaser is really awesome, making it super easy to create a game using few lines of code.

- adds .npmignore files to ignore the files which are for development and not needed by npm
- adds a `main` field in package.json, so that phaser could be installed by [browserify](https://github.com/substack/node-browserify) or [cortex](http://ctx.io).
- npm on longer allow uppercase package name, so I rename it as a lowercased one.