Modify functional tests to use Surefire/Failsafe plugin

When running functional test inside of Maven Antrun plugin, whatever the results are, control flow continues. Additionally, the resulting summary for each example is not visible.

The decision was to migrate functionality to Failsafe plugin, because it grants undeploying the archive/stopping Selenium server even if integration testing itself fails. Failsafe acts as Surefire, so its reports are familiar to other developers.

If functional testing fails, Maven ends up with failure message. This is the intended behavior.