release 4.2.7

[cehbrecht]

Overview

This PR prepares release 4.2.7.

Related Issue / Discussion

542

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.
• [x ] I have already previously agreed to the PyWPS Contributions and Licensing Guidelines

[cehbrecht]

@tomkralidis @jachym @ldesousa ok to make a patch release 4.2.7?

[coveralls]

Coverage remained the same at 75.589% when pulling d1b879f11d531e7d994c2b4eb2d6e8e350347255 on cehbrecht:prepare-release-4.2.7 into 685c49fb35960604d765af9918c49cde4a273825 on geopython:pywps-4.2.