Update CI config

[ashfurrow]

Discussed here and below, our CI is borked. It's linked to from the readme. It doesn't even appear to be configured. We should fix it.

[rynecheow]

The SPM proj is not needed to be commited - as it can be pregenerated before running the SPM step. I’ll raise a PR to remove it.

[rynecheow]

@ashfurrow The last tracked bit of the SPM proj has been removed dd84794 - this shouldn't be blocking Carthage installs anymore

[ashfurrow]

Sounds good – but we're still failing on Circle:

No .circleci/config.yml was found in your project. Add a configuration file to your repository or refer to documentation.

I think we just need to set up CI. I'll update the issue title to match.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[ashfurrow]

Still needs to be updated.