MWMediaSearchWidget: Use json/jsonp for local/foreign api respectively

In the media search widget use 'json' for remote searches and
'jsonp' for local searches.

Bug: 64822
Bug: 67749
Change-Id: Iccc9adb1261602f4bc7426f1caf5aed87aad51e5
Merge "MWMediaSearchWidget: Use json/jsonp for local/foreign api respectively"