MAIN-3096: Pass correct path-prefix when making a request to Vignette

Vignette requires to pass correct path-prefix to it when sending a request. For unknown new galleries in VE were not tested in different languages than EN and this problem didn't pop out (path-prefix for English is null).

https://wikia-inc.atlassian.net/browse/MAIN-3096
MAIN-3096: Sometimes I forget spaces here and there. That's how I rock.
Merge pull request #5235 from Wikia/MAIN-3096

MAIN-3096: Pass correct path-prefix when making a request to Vignette