refactor(demos): use angular modules

The old demos works good, but creating controllers that way is not the recommended way, not even for demos. So I modified all of them to use proper angular modules. I think that the result is now better (before we had two different types of conventions for controllers and now we have just one and better one).

I also modified the plunker generator to use the same module as the demo page (so the demos won't break up on plunker).

This closes #1884