Fix for #584

This change set addresses the issue identified in #584.

Switched off constraints were being supressed in JSON output since the `PathQuery::getJson` method was/is being used in the webapp to supply the query definition to the tables. This needs the switched off constraints removed. Calls to "GET /templates" on the other hand need the full template definition.

This has been resolved by:
 * Making the clients more forgiving, and filtering out switched-off constraints used to construct queries in imjs (see 2.10.8 and 3.2.2)
 * Having the calls to "GET /templates" render a full version of the template, but leaving `::getJson` alone for backwards compatibility.

A test case is provided here in the testmodel so that this can be examined in the iodocs API explorer. Test cases for the client parsing are provided in those repositories.