Dropping support for win-32 and ppc64le

[pseudoyim]

We have been building geoviews packages as noarch since v1.6.2.
https://anaconda.org/anaconda/geoviews/files?sort=basename&sort_order=asc

After the noarch package builds, we test the package on various platforms. The tests on win-32 and ppc64le fail (as of today) because of missing dependencies on those platforms. We have decided to ignore those test failures and upload the noarch package to defaults anyway because:

• ppc64le boxes won't normally have a graphics card, so most people should not be attempting to use geoviews on such systems
• win-32 support will soon be phased out