Add package.json for publishing as node module

Add a new package.json which allows publishing the project as a npm
package to be used in other web projects. The sass/css is is part of the
npm package to allow projects to re-use sass or simply import the css
file.

Closes: #3

README.md

+# Arch Linux common CSS Styles
+
+Common Arch Linux SASS and CSS styles.

package.json

+{
+  "name": "archlinux-common-style",
+  "version": "0.0.1",
+  "description": "Common Arch Linux CSS Style",
+  "main": "sass/archlinux.sass",
+  "repository": {
+    "type": "git",
+    "url": "https://gitlab.archlinux.org/archlinux/archlinux-common-style.git"
+  },
+  "author": "Levente Polyak",
+  "license": "MIT",
+  "scripts": {
+    "build": "make css"
+  },
+  "files": [
+    "sass",
+    "css",
+    "README.md"
+  ]
+}