Single Post View WIP

Second stab at this. This is a different approach at the problem; rather than trying to revert back to a "Pre-Backbone" single post view, this instead is an attempt to restyle the layout to feel much more natural and less invasive. I'd like to make a balance between legibility and ease of composing responses.

DONE:
1. Disabled post-nav in Single Post.
2. Restyled comment box.
3. Interaction pane is now permanently open, and stands at full height without the need to scroll.
4. Because this is now based on the Single Post View in upstream, no tests should fail on it.
5. Improved typography of post, may need a second go-around just for the sake of being uniform with the rest of the application.
6. Remove unnecessary hiding/invoking functionality for comments, as that's no longer needed.
7. Interactions pane now sits directly under the body of the posted content.
8. All posts now use the same template, meaning no more wallpaper posts.
9. Incidentally, embedded videos look nicer with the unified post template.
10. Remove processing for text header, which currently is done after the first line break in a post.

TODO:

1. Ensure comments are in proper order (mine for some reason are in reverse order somehow?)
2. Make clicking the comment icon automatically scroll to comment box (maybe something like scroll-spy would be useful here?)
3. Comment box currently shrinks while it's being typed in (probably a styling issue, just needs some tweaking)
4. Bring in the Navigation header used in the rest of Diaspora, for easy-access to messages, notifications, contacts, and settings.
5. Strip out unused post-picker templates.


![single-post-view-body](https://f.cloud.github.com/assets/401560/109666/759f0d66-6a8d-11e2-900a-e4e7c7d9d4e9.png)
![single-post-view-commentbox](https://f.cloud.github.com/assets/401560/109667/791e2b2a-6a8d-11e2-85f5-dc22541b0ab9.png)