Replace play icon font with svg

## What does this MR do?
Replaces the `play` font awesome icon with svg

## Are there points in the code the reviewer needs to double check?
Make sure that the svg is looking great on all the changed pages

## Why was this MR needed?
SVG is better than fonts 😄 

## What are the relevant issue numbers?
 #21455 

## Screenshots (if relevant)
Before (Pipeline):
![Screen_Shot_2016-08-26_at_4.16.16_PM](/uploads/90a75b91b516e643f2134e053b0d7590/Screen_Shot_2016-08-26_at_4.16.16_PM.png)

After (Pipeline):
![Screen_Shot_2016-08-26_at_4.15.49_PM](/uploads/44e44a3d4c14066b8b7ec8c3da36e012/Screen_Shot_2016-08-26_at_4.15.49_PM.png)

Before (Environments):
![Screen_Shot_2016-08-31_at_3.03.35_PM](/uploads/bd4087a9f01c1a4d3c373d2662df4fe5/Screen_Shot_2016-08-31_at_3.03.35_PM.png)

After (Environments):
![Screen_Shot_2016-08-31_at_3.00.23_PM](/uploads/0ec45031bedb271f16bea3544cbfe52b/Screen_Shot_2016-08-31_at_3.00.23_PM.png)

## 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 !6038