Updates covmodel reference, adds cleanup

Tests running [here](http://buildbot.oceanobservatories.org:8010/builders/coi_any/builds/103) and [here](http://buildbot.oceanobservatories.org:8010/builders/coi_smoke/builds/2864).

The referenced changes are [here](https://github.com/ooici/coverage-model/commit/11944dd53b0883a996182fbeb27acb0652fa3b5f)
Part of [OOIION-1302](https://jira.oceanobservatories.org/tasks/browse/OOIION-1302)