Get rid of jQuery dependency, use Riot object as a namespace

I think that it's within the Riot's spirit to make no assumption about what DOM manipulation library one should choose. Riot should be simple and welcoming to any choice.

This will also prevent a lot of raised eyebrows when newcomers will see `$.route` (jquery route? what?)

However, to implement that, we need a namespace in which Riot will live, therefore `global.Riot`. This will also allow  to add extensions easier, since you won't have to pollute the DOM library with foreign code. Everything that belongs to Riot should be in Riot namespace, simple as that.

Whether you accept this change or not, it's up to you.

PS: I've removed some random empty lines for consistency.