Keep not ewoks properties apart from pure workflow descrptions

As discussed here the json describing the workflow should contain only ewoks-specific properties in order to be clean and human-readable.

For that execution parameters, worker-options and gui-settings must be kept in another json file that will be connected through the same id with the actual workflow description.

Ewoksserver will be able to provide the clean ewoks description as well as the combined json description for ewoksweb to correctly visualize the workflow.

Any new addition for specific use-cases like the dataportal schemas has to be treated the same way. For that we can discuss having in our configuration file the extra properties that are added in our specific installation each time. These will be saved in a different file and accessible through the API. It provides a dynamic way to add properties in workflow descriptions not related to ewoks and still keep ewoks description clean.