Fixed code and tests related to previous pull request (redux)

Previous pull request resulted in these failures:

https://travis-ci.org/geopython/OWSLib/jobs/43545711#L415

https://travis-ci.org/geopython/OWSLib/jobs/43545711#L442

Which have been addressed in this new pull request.  Did a rebase so that this PR does not rewrite history.
`timeout` should actually be in the constructor now (per https://github.com/geopython/OWSLib/pull/199#commitcomment-9002040), so:

```pycon
wfs = WebFeatureService('http://SDMDataAccess.nrcs.usda.gov/Spatial/SDMWGS84Geographic.wfs', version='1.0.0', timeout=360)
response = wfs.getfeature(typename=('MapunitPolyExtended',), filter=wfs_filter, propertyname=None)
```