0.8dev updates for examples

(Now rebased on 0.8dev) These commits add changes required to get all the examples running (as much as I could). Some notes:

geohashart doesn't run because of a cross origin error, not sure why?
sochistats doesn't run because the data doesn't load, some kind of API error
weather doesn't seem to do much
There are some outstanding issues that I have noticed

in many of the examples, hovering over markers causes them to disappear or change style (permanently becoming black). I wasn't sure what triggered the hover behaviour, I suspect that the problem has to do with how patterns, fills etc are added to and removed from the _defs object in the renderer.
some of the examples seem to run really slowly when interacting with the map (pan, zoom etc). I'm not sure if this is a regression or not - I tried to run the conflictdata example from the hosted version and it crashes chrome (Aw, snap). The 0.8 version does run, but zooming or panning is very slow and sometimes crashes the tab.