update owslib.util.http_post to configure redirect behaviour

[tomkralidis]

This PR add an allow_redirects argument to owslib.util.http_post to enable callers to configure accordingly.

[geographika]

I presume this is to allow users to disable redirects (as the requests default is True)?

Notes to self: https://requests.readthedocs.io/en/latest/user/quickstart/#redirection-and-history

https://requests.readthedocs.io/en/latest/api/#main-interface:
allow_redirects (bool) – (optional) Boolean. Enable/disable GET/OPTIONS/POST/PUT/PATCH/DELETE/HEAD redirection. Defaults to True.

[tomkralidis]

I presume this is to allow users to disable redirects (as the requests default is True)?

Notes to self: https://requests.readthedocs.io/en/latest/user/quickstart/#redirection-and-history

https://requests.readthedocs.io/en/latest/api/#main-interface: allow_redirects (bool) – (optional) Boolean. Enable/disable GET/OPTIONS/POST/PUT/PATCH/DELETE/HEAD redirection. Defaults to True.

Yes, in the context of providing downstream applications safeguarding (example is pycsw harveesting).