Cmorizer for the PERSIANN-CDR precipitation data

[hb326]

Tasks

• Create an issue to discuss what you are going to do, if you haven't done so already (and add the link at the bottom)
• Give this pull request a descriptive title that can be used as a one line summary in a changelog
• Make sure your code is composed of functions of no more than 50 lines and uses meaningful names for variables
• Circle/CI tests pass. Status can be seen below your pull request. If the tests are failing, click the link to find out why.
• Preferably Codacy code quality checks pass, however a few remaining hard to solve Codacy issues are still acceptable. Status can be seen below your pull request. If there is an error, click the link to find out why. If you suspect Codacy may be wrong, please ask by commenting.
• Please use yamllint to check that your YAML files do not contain mistakes

New data reformatting script

• Test the CMORized data using recipes/example/recipe_check_obs.yml, to make sure the CMOR checks pass without errors
• Add the new dataset to the table in the documentation
• Tag @mattiarighi in this pull request, so that the new dataset can be added to the OBS data pool at DKRZ and synchronized with CEDA-Jasmin

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Closes {Link to corresponding issue}

[bouweandela]

Looks good to me! @mattiarighi Could you please test and do scientific review?

[axel-lauer]

Testing this right now...

[axel-lauer]

The test was successful, the cmorizer does what it is supposed to do. Thumbs up!