[new] geo/py-owslib

Hi,

here's a new port for OWSLib (http://geopython.github.io/OWSLib/), a
runtime requirement for QGIS3. Builds fine, i kept the casing for the
upstream distname (ie PKGNAME=py{,3}-OWSLib), but the directory name is
py-owslib, dunno what would be better..

comments welcome.

Landry