Only apply masonry JS to index pages, widen `.box`es on permalink pages.
Add permalink page HTML mockups for all, photo, and text post types.

This commit adds three new HTML mockups, although one is merely a
convenience template. Specifically, `web/permalink.html` provides a
single file in which all post types can be prototyped. The
`web/permalink-photo.html` and `web/permalink-text.html` files showcase
the desired Tumblr-generated markup for a permalink page of the photo or
text post type, respectively.
Remove "Your photos" heading from permalink post types except "photo".