Change logo animation to CSS

## What does this MR do?
Converts the tanuki logo animation from javascript to CSS. You can now animate the tanuki svg logo by adding the CSS Class `animate`to it.

## Are there points in the code the reviewer needs to double check?
Just need to double check for browser compatibility

## Why was this MR needed?

*  Using CSS for simple animations is a best practice (Optimizes DOM, uses GPU to do animation rather than CPU)
*  Happy DOM 🎈 

## What are the relevant issue numbers?
Closes #20607 

## Screenshots (if relevant)
Before DOM
![8BrOJAqT4U](/uploads/705a3c7b53c45d32d435cafecfc958bd/8BrOJAqT4U.gif)

After DOM
![Screen_Shot_2016-08-03_at_10.30.08_PM](/uploads/e82d9b63501def4dc4e67a5659863680/Screen_Shot_2016-08-03_at_10.30.08_PM.png)

Before
![JnEgliIIVO](/uploads/39aaec48fd3e193f20cf455371ea2d13/JnEgliIIVO.gif)

After (Basically the same, hard to tell in my gif though because it was hard to get the timings right on the recording)
![fvLeXxmp3U](/uploads/058cf15fffed4be549af2e963eca4412/fvLeXxmp3U.gif)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] All builds are passing
- [x] 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 you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5655