[fix] Fix select fields in Device config editor #910

For select fields, with predefined values in the corresponding JSON
schema, when a value is saved other than the default, the field will
be empty after saving in the Device config editor. This happens only,
in combination of the lib select2.  The cause of the issue is, that
the jsonschema-ui.js version does use a deprecated way to initialize
select2 inputs. This commit will fix this issue by updating the way of
initializing the inputs.

Fixes #910

Signed-off-by: Konrad Kreitmair <[email protected]>