Dependency version conflict with PyCSW

Depending on the version of PyCSW you install, you may encounter a problem running the `ckan-pycsw` paster command with:

```
pkg_resources.ContextualVersionConflict:
(OWSLib 0.8.6 (/usr/lib/venv/lib/python2.7/site-packages),
Requirement.parse('OWSLib==0.16.0'), set(['pycsw']))
```

This is because ckanext-spatial requires 0.8.6 whereas pycsw after a certain version uses more recent OWSLib.

---

I've worked around this by installing a newer OWSLib, not yet sure what effect it has on the running of ckanext-spatial.

Start by reproducing the `ckan-pycsw` paster command with the reported PyCSW and OWSLib versions. Inspect the dependency requirements for ckanext-spatial and PyCSW, then verify a compatible resolution without breaking ckanext-spatial; the issue provides no file or test path.

Written by the indexing model from the issue text.