Revert to lowercase NPM package name

As per https://docs.npmjs.com/files/package.json#name as mentioned by @Pumpuli
in #845.

Gruntfile.js

@@ -108,7 +108,7 @@ module.exports = function (grunt) { // eslint-disable-line
 			options: {
 				banner: [
 					"/*",
-					pkg.name + " v" + pkg.version,
+					"Mithril v" + pkg.version,
 					pkg.homepage,
 					"(c) 2014-" + currentYear + " " + pkg.author.name,
 					"License: " + pkg.license,

package.json

@@ -1,5 +1,5 @@
 {
-  "name": "Mithril",
+  "name": "mithril",
   "description": "Mithril.js beta build - use this to help us test the releases before they are released",
   "version": "0.2.1",
   "homepage": "http://mithril.js.org",