Fix Utils::serviceUrl()

Summary:
I wasn't able to reproduce the \url() issue, so it is
a naive fix. We just don't use \url().

Test Plan: ./phpunit

Reviewers: #hkccp_developers, vanmeeuwen

Reviewed By: #hkccp_developers, vanmeeuwen

Subscribers: #hkccp_developers

Differential Revision: https://git.kolab.org/D1600