Add elixir file type icon

[simov]

Fixes: #299

Just the icon.

You can push to this branch if anything else is needed.

[ctf0]

try to add the lang config as well to test if you can see the icon of not

[simov]

There is the config and the icon is showing up, though it's too dark to actually see it. I tried to find a brighter logo icon with no luck.

[ctf0]

you can edit it with photoshop or somthing to brighten it up a bit if you want