Fix appearance in error pages

## What does this MR do?
The error pages under `app/views/errors/*` looks like the error page for 404 `public/404.html`

## Are there points in the code the reviewer needs to double check?
I restructured how the GitLab logo is shown in the `public/404.html` and all the pages under  `app/views/errors/*`.

## Why was this MR needed?
#24363 
## Screenshots (if relevant)
Before
![Screen_Shot_2016-11-10_at_11.11.48](/uploads/b134195dd2d63d093ec0a6d906761e3f/Screen_Shot_2016-11-10_at_11.11.48.png)

After
![Selection_064](/uploads/d57601513d6ab3c0b5e1c7448ecf6ffc/Selection_064.png)![Selection_057](/uploads/50220320bad0b1c14ec8d1e89e490373/Selection_057.png)![Selection_060](/uploads/1e04e4ce36ef7fa5bee4e7916b0e5de2/Selection_060.png)![Selection_059](/uploads/0a4a02a8bae132232d4331adce132d4a/Selection_059.png)![Selection_062](/uploads/3d96f0e8c0e5f0f73b3b51cbb168c76a/Selection_062.png)![Selection_061](/uploads/e127a2b2acc810a9176d02927f1c8dbc/Selection_061.png)![Selection_063](/uploads/e3f682c293539ff195a78018da872abf/Selection_063.png)


## Does this MR meet the acceptance criteria?

- [X] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [X] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [X] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

See merge request !7635