release 4.2.4

[cehbrecht]

Overview

Prepared release 4.2.4:

• updated version
• updated changelog

Related Issue / Discussion

Additional Information

Contribution Agreement

(as per https://github.com/geopython/pywps/blob/master/CONTRIBUTING.rst#contributions-and-licensing)

• I'd like to contribute [feature X|bugfix Y|docs|something else] to PyWPS. I confirm that my contributions to PyWPS will be compatible with the PyWPS license guidelines at the time of contribution.
• I have already previously agreed to the PyWPS Contributions and Licensing Guidelines

[cehbrecht]

@jachym @tomkralidis I have prepared the 4.2.4 release. Could one of you merge this PR and make the release?

I suppose our agreement in PR #505 for this release is sufficient.

[coveralls]

Coverage remained the same at 75.618% when pulling c109840 on cehbrecht:release-4.2.4 into cbca3cf on geopython:master.