Update the CDAT installation steps

[jypeter]

@stefraynaud I have checked your 1.2.1.2. Install UV-CDAT and it's a bit out-of-date

• UV-CDAT is now only called CDAT (you may have references to "UV-CDAT" in other parts of the documentation)
• I'm not sure the install command you specify stills works. You mention conda install -c uvcdat uvcdat but I have used conda create -n cdat-8.1_py2 -c cdat/label/v81 -c conda-forge python=2.7 cdat (for a full installation in a new environment). You may want to check the install steps on the official page (though I have told Charles this needed some improvement as well)
• You should probably just remove the "install CDAT from source" as this is not really documented (if it is possible) any more

[stefraynaud]

The UV-CDAT installation page must be removed. In fact, as it is done in travis, not the whole cdat metapackage is installed, but only a selection along with other packages:

vacumm/.travis.yml

Line 21 in afa8c37

- conda create -q -n test-environment -c conda-forge -c defaults --override-channels python=$TRAVIS_PYTHON_VERSION cdms2 cdutil genutil esmpy configobj paramiko xlutils seawater pytz cmocean basemap-data-hires matplotlib scipy pytest

I'll update the doc to make it clear.