allow app parameters to be defined by spel

[parisni]

currently app parameters are statics. Would be nice to allow spel to generate the parameters.

  parameters:
    definitions:
      - id: myParameter
    value-sets:
      - values:
          myParameter: #{myCsvList}

[LEDfan]

We could add this feature, but it would be good to know how you would this feature.
What values would you use in the SpEL expressions? The parameters must be generated before the app is started, therefore the only input to the SpEL expression would be the information of the current user. Would this be sufficient?