Added 0.4.0, kept 0.2.1
Package.json: + "keywords": "tutorial", MIT Licence (stated in intro.js)
intro.min.js: + comment line for file name, version, (c), licence
Merge pull request #1426 from tomByrer/master

Intro.js: added 0.4.0, minor tweaks to Package.json, intro.min.js