WS-1405 Fix matrix service's CAPO properties

A followup MR was bound to happen.

I was setting variables to CAPO property values in the constructor so the service wasn't picking up on changes to these properties until I kicked it. This should fix that, but let me know if I'm crazy. I tested it by trying to get versions after changing the casa_root in the CAPO file while the container was up and verified the change.

Also found an index out of bounds error when not passing a capability. Passing a capability is a requirement now and I'll update the swagger docs with the README MR.