Ground dependencies and remove extras

[calina-c]

Closes #1302. Closes #1305

Still pending:

• update the classifier regarding release status from pre-alpha (to what?) -> see https://pypi.org/classifiers/
• should we keep the original package author?
• coloredlogs, used in testing settings, introduces both the dependency to coloredlogs and pyyaml to setup a yaml log file. I have never seen this file, are we using it? We should look into removing those dependencies if not essential, or at least downgrade them to dev/test dependencies if they belong there. (experimental branch exists for this)

[LoznianuAnamaria]

Blocker for: #1203

[trentmc]

• update the classifier regarding release status from pre-alpha (to what?) -> see https://pypi.org/classifiers/

I'm fine with either of:

• Development Status :: 4 - Beta
• Development Status :: 5 - Production/Stable

And I lean to (4) for now.

We can get to (5) when installing ocean.py is less finicky, which includes:

• it's got so stable that the "install" readme can be just a single line pip install ocean-lib rather than half a page of gotchas & workarounds, AND
• ocean.py runs out-of-the-box on anaconda (this is more useful than you may realize: once we have this, we can get teed up to be part of the conda distribution itself)

[trentmc]

should we keep the original package author?

What's the motivation to change it?

FWIW, I think "leucothia" is hard to pronounce or understand why it's named that way. Better is "ocean-core-team" or something