Issue warning instead of an error.
Added `test_formula_terms_ap_missing_coords`.
4 ocean vertical coordinates factories.
Fixed __future__ import check failures.
Added lazy nc data saving.
Updated travis-ci dependency for biggus.
Only streamed the save through biggus when we have lazy data.
Fixed failing Saver test, updated doc.
Merge pull request #1505 from pelson/lazy_save

Lazy save
Merge pull request #1485 from ocefpaf/no_error4coordfac

Issue warning instead of an error.
Merge pull request #1304 from ocefpaf/ocean_vertical_coordinates

4 ocean vertical coordinates factories.
Remove SSL workaround
Merge pull request #1507 from rhattersley/remove-ssl-workaround

Remove SSL workaround