Decide whether to change method for getting some beamline parameters

[dperl-dls]

To specify a list of beamline parameters to get, it's nicer to use an array in the body of the request. This is fine for most cases, but browsers don't generally support adding bodies to GET requests. This operation is clearly a GET, though.

[dperl-dls]

some debate here: https://stackoverflow.com/questions/2602043/rest-api-best-practice-how-to-accept-list-of-parameter-values-as-input