Adds ion-functions submodule

Should fix the builders after [this commit](https://github.com/ooici/marine-integrations/commit/4b921d10dcee876608f94bd60e0bbad44907160b)

Remember to:
```bash
brew tap lukecampbell/homebrew-libgswteos
brew install libgswteos-10
brew test -v libgswteos-10
```