Coverage reports

[edaub]

I can't seem to figure out why the coverage reports aren't uploading. A couple things to explore:

• Can I just install firedrake manually within the travis build? Coverage reports seem more straightforward if not in a docker container.
• I managed to get things working before on the travis branch, then they stopped. Look back at that commit and what changed after that to get some ideas.
• Keep tweaking? I don't know why I can never get the bash uploader to work...