Update guides

Quite some visual changes to the layout of guides, to start bringing them more in line with visuals [defined here](https://www.loomio.org/d/iHfFyrsk/growing-guides-interface).

![screenshot 2014-10-05 15 56 56](https://cloud.githubusercontent.com/assets/485583/4518039/d683568c-4c6d-11e4-87d6-050c9524aad5.png)

# What's changed
* Visual changes, primarily, there is now a "canopy" which includes a twitter / facebook style full width image, which is the featured image. This defaults to a canopy grey-leaf.
* Started to pull out getting guides and users into an angular file, just to stay a bit dryer. I'm not sure whether this is the right way, I'm treading on new ground here for myself (should probably have more promises, I'll take any input).
* Markdown gets recognized in output of overview and of stages.

# What's next
* More of the same, just want to start getting some feedback in.