New single post view

This is about this bug: https://github.com/diaspora/diaspora/issues/3741

I implemented most of the proposal [here](https://wiki.diasporafoundation.org/images/e/eb/Spv-sean-jonne.png). As you can see, it is based on https://github.com/diaspora/diaspora/pull/4390, as I require the header changes anyway.

The implementation is pretty straightforward and tries to reuse as much from other components/views as possible, so this has a working lightbox, oembed etc. Please take a look at it and comment on questionable/wrong/erroneous parts. 

My placement of the css code is probably not quite right, I don't really understand the SCSS structure and would appreciate it if someone could take a look at it.

Specs still run after small changes.

Things that are missing or have to reworked:

* Vestiges of the old SPV have to be removed.
* CSS for oEmbed videos needs to be adjusted.
* Micro pictures of commented users are not unique, so a user that does three comments will appear three times. I don't know if this should be changed or not.
* Probably more specs should be written, but I'm not that familiar with jasmine. Maybe someone else can take a look at it or point me in the right directions.
* Comments/Posts can not be removed.
* The post always displays, nsfw or not.
* The vertical line between post content and interactions is only as high as the post content div. This needs some css hacking.

Having said that, it is already much nicer to use than the old SPV. Please review, so we can get it merged soon.

Here are some images that show the current look.
![spv3](https://f.cloud.github.com/assets/101936/981027/ffe246cc-073c-11e3-98f3-13451bc6a201.png)
![spv2](https://f.cloud.github.com/assets/101936/981028/fffd37de-073c-11e3-857d-2eb9904b444d.png)
![spv1](https://f.cloud.github.com/assets/101936/981029/00163d6a-073d-11e3-8963-f1711c79ca81.png)