[WIP] Unify not connected pages

After a discussion with @jhass about https://github.com/diaspora/diaspora/pull/5389 he pointed that it would be better to first unify every pages with the current design (white background, black text).

So here we are:
**Registration page**
![registration](https://cloud.githubusercontent.com/assets/930064/4992726/07983086-69a5-11e4-9afe-19c73c19bb7e.png)

**Connection page**
![connection](https://cloud.githubusercontent.com/assets/930064/4992727/10e19c9a-69a5-11e4-92b2-79639d76281f.png)

**Password recovery 1**
![password1](https://cloud.githubusercontent.com/assets/930064/4992728/1e43d100-69a5-11e4-8675-dca903761eb7.png)

**Password recovery 2**
![password2](https://cloud.githubusercontent.com/assets/930064/4992731/285132c8-69a5-11e4-8881-3fade581e9ef.png)

Old page was like that:
![old-pwd](https://cloud.githubusercontent.com/assets/930064/4992743/419b61ea-69a5-11e4-805b-30c42a6dd4e1.png)

The "diaspora*" on the screenshots is the podname.



why is this better than `display: none`?