If alerts

We now have two types of alert. I've made them a component and will go around and update other alerts in apps to use the new ones. I know there were some issues with alerts in thorntree using hyperlinks and not working with a component so will look at that (still useful everywhere else).

I also removed a couple of old and pointless typography variables.

![image](https://cloud.githubusercontent.com/assets/814861/3808468/ebe8bccc-1c77-11e4-8f6c-d131a0dcc6f0.png)


Yeah, although I'm not sure how that really helps the logic-less nature because all you're doing is moving the logic rather than removing it.

I think a ui_classes object would be even nicer, so you would call `ui_classes(alert)` or `uiClass.alert` or something like that but it would only be worth doing if this was a good idea