(bug 31644) Apply wfExpandUrl() to url in api result of GlobalUsage
(bug 31644) Apply wfExpandUrl() to url in api result of GlobalUsage

* we can use PROTO_CURRENT because cache is fragmented over http/https for api
* This is required to make sure that we can return protocol relative URLs

Change-Id: I804b27d74e797491aa7f1452cb7964237f0cd198

WouterRademaker/mediawiki-extensions-GlobalUsage,wikimedia/mediawiki-extensions-GlobalUsage,wikimedia/mediawiki-extensions-GlobalUsage,WouterRademaker/mediawiki-extensions-GlobalUsage