Date in odk docker container is not the same as outside

Noticed by @kltm and @dougli1sqrd

Note we make use of the current date to set the versionIRI:

```
TODAY := $(shell date +%Y-%m-%d)
```

one thing to be aware of (this is from west coast)

```
~/repos/go-ontology/src/ontology(master) $ date
Mon Jun 24 16:13:53 PDT 2019
~/repos/go-ontology/src/ontology(master) $ docker run --rm -ti obolibrary/odkfull date
Mon Jun 24 23:13:58 UTC 2019
```

This is not necessarily wrong or particularly unexpected, but release managers should be aware of this. If I was to start making a release at 5pm I may be surprised to see tomorrows date. Or if I started 4.55pm, abandon part way, resume at 5pm, my versionIRI tags for different artefacts will be off.

This was noticed on the go pipeline, which is executed automatically rather than by a release manager.

Maybe we should encourage clients to set TODAY from outside so they have total control

Start by reproducing the displayed `date` comparison between the host and `obolibrary/odkfull` container, then inspect the Make assignment `TODAY := $(shell date +%Y-%m-%d)` and how the automated go pipeline uses it. Define a consistent, controllable date source so resumed or automated releases cannot produce conflicting versionIRI dates.

Written by the indexing model from the issue text.