Prudhomm/issue1533

[prudhomm]

• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes?
• Have you successfully run the Feel++ testsuite with your changes locally?
• Have you written Doxygen comments in your contribution ?

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This involves

• add interface to set ModelProperties from filename and json  #1533
• add interface to set a config file  #1534

This PR allows to handle situation where we don't have access to command line options such as in ipython or colab.

regarding #1533 it allows to change the json to our liking and run the simulations without having to save the json and load it with the command line options