JSON output should include only relevant items

[hanecak]

We have content negotiation for result pages implemented. HTML and JSON output is possible.

For example:

curl http://odn.opendata.sk/odn-search/item/org_1093768

returns:

[{"id":"org_1093768","type":"ORGANIZATION_RECORD","name":"Utopia","legal_form":"Združenie (zväz, spolok, spoločnosť, klub ai.)","seat":"Lipského 2,  841 01 Bratislava - Dúbravka","ico":"42178509","date_from":"Mar 5, 2010 12:00:00 AM","donation_value":0.0,"price":0.0,"vat_included":false}]

Problem is, items NOT relevant for organization entry (type ORGANIZATION_RECORD) are included too, i.e. "donation_value" and "vat_included".

We need to fix that so that only relevant items are included.