Adjust URL to use frontend only in case we use appium. In all other cases keep u…
…se default way to provide backwards compatability.
This commit fixes backwards compatibility after a regressions introduced in !109 (closed).
Following test results prove it works:
https://nexedi.erp5.net/test_result_module/20161104-7A7E676
https://nexedi.erp5.net/test_result_module/20161104-15D828A5