Add a support status banner to the admin dashboard

Review Request #1234 — Created May 16, 2018 and updated — Latest diff uploaded

Review Board
The support banner shows the current support status, via's API. While the data is being retrieved, a spinner is
being shown.

Testing Done:
Tested the banner with:

- an active support contract;
- an inactive support contract; and
- no support contract.

Reviewed at