[SITE-2846] Fix admin bar item layout issue

[cbirdsong]

The Pantheon logo pushes the environment label out of the admin bar item if the theme has this fairly common bit of CSS:

img {
  display: block;
}

Adding display: inline-block; to the icon fixes it:

[jazzsequence]

Thanks for the PR @cbirdsong
Tagging @pwtyler for 2nd approval.

[westonruter]

I just opened a PR (#146) to fix the same issue, and then I saw this PR!

[jazzsequence]

we've updated our GH policies to require 2 approvals on all PRs which is pretty much the main reason this hasn't been merged yet. When we can get another ✅ this will get merged and released. Hang tight, y'all.