fix cdata deserialzation

[cehbrecht]

Overview

This PR fixes issue #553. It removes the CDATA tag when loading an input from json.

Related Issue / Discussion

553

Additional Information

https://github.com/roocs/rook/pull/72

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

[coveralls]

Coverage increased (+0.04%) to 75.484% when pulling 86f96a0c3c7875df0c5c43a67279c347d2bde4af on cehbrecht:fix-553-json-with-cdata into 9fa56cc17bf545a9a583271d83affa5b479d3373 on geopython:pywps-4.2.

[cehbrecht]

Note that another, maybe cleaner option, would be to set the CDATA tag into the xml template, instead of the json representation.

I might have tried to do that originally but could not get all the kinks out. It might be more difficult though to code the necessary logic inside the template.

I have opened an issue for this #557.