Remove some deprecated things in `units` and `wcs`.
Change time format from iso to isot in time docs example
Merge pull request #2435 from bsipocz/changing_time_example

Change time format from iso to isot in time docs example
Merge pull request #2386 from mdboom/misc/remove-deprecated-0.4

Remove things that were deprecated in 0.3
Added Redshift model for wavelength.