New advertising page

Big redesign of the /advertising page.  

[huge screenshot for reference](http://i.imgur.com/DWgyyju.png)

You can safely ignore the first commit, as it is just the commit from this PR that I never got around to pushing out prior to this: https://github.com/reddit/reddit-plugin-about/pull/39.  This also depends on https://github.com/reddit/reddit-public/pull/2347 and https://github.com/reddit/reddit-plugin-gold/pull/31

There are obviously a lot of stylistic changes, but the ones I'm most concerned with are the ones in python, specifically:

* sourcing ad links from a subreddit
* sourcing almost all other text content on the page from a few different wikis

Having spent a larger portion of my time thus far doing design work, my python chops are still rough, so pay extra attention there please.

:eyeglasses: @ajacksified @spladug @umbrae @bsimpson63
for the call to `WikiPage.get` in `WikiPageIniItem`.  Previously, the use of `Frontpage` was baked in, but when I move it to the main repo in https://github.com/reddit/reddit-public/pull/2347 i was unable to import `Frontpage` into its new home.  

old
https://github.com/reddit/reddit-plugin-gold/blob/master/reddit_gold/models.py#L35

new
https://github.com/madbook/reddit-public/blob/move-WikiPageIniItem/r2/r2/models/wiki.py#L468