Add build system

Adding a build system:

- use npm to manage dependencies of build system
- use bower to manage dependencies of ap itself (e.g. jQuery)
- use grunt for build automation

I replaced the index.html with a new file as the build system requires some specific annotations.

I had to convert all line endings. Please configure your local git to not change them again.

I haven't changed anything in any of the JS files besides fixing the path of the images to images/dungeon.png, etc.

I moved the canvas styling to the CSS file.

See README for build instructions.