use the same app tiles everywhere (step 1)

Apologies of the size of this PR but it's the first step of unifying the app tiles across Fireplace and it will end with the unspecification (and much style removal) of feed.styl.

Most things should be visually unaffected (some alignment issues were resolved) except for the search results. The next steps are to make the mini tiles be the same and make the grid/grid-if-desktop styles be the ones used in the feed. It will probably be a good idea to merge this locally for testing as it touches a lot of areas but I tested on both mobile and desktop: detail page, home page, my apps, search, new/popular, category pages.

![](http://f.cl.ly/items/281X401x1v1k2e140L3t/Image%202014-09-29%20at%2011.30.24%20AM.png)

![](http://f.cl.ly/items/19361E0H3G1J1u2i1o2m/Image%202014-09-29%20at%2011.33.17%20AM.png)
Mini tiles are going away from feed.styl in the next pass. If their dimensions are needed elsewhere we should move the constants to a lib for sure.