Fix assignment of phylesystem-1 access on GitHub

I believe I've found the most likely cause of the unnatural lag between the main `phylesystem-1` repo on GitHub and its clone on **api.opentreeoflife.org**. It looks like we're trying to push to remote with the wrong keyfile. You can see this by using cURL to call the API method for syncing repos:
```bash
$ curl -X PUT http://api.opentreeoflife.org/phylesystem/push/v1
```
The push fails because we're blocked from using the `repo-phylesystem-0.pem` key here:
```
ERROR: Permission to OpenTreeOfLife/phylesystem-1.git denied to OpenTreeOfLife/phylesystem-0.
fatal: The remote end hung up unexpectedly
```

Assuming I've specified to proper .pem file, this should allow us to push changes properly from the local (phylesystem-api) repo to the remote on GitHub.