functional tests fail in headless env.

I cloned the repo and ran grails test-app and everything worked fine. I tried the same in a headless env. and the functional tests failed, so I guess it's the fact that the env. is headless that's the cause of the failure.

I know some people have successfully run Geb tests in a headless env. using either a headless browser (e.g. PhantomJS) or by using XVFB to emulate a display. As a point of reference, it would be really helpful if these Geb tests worked in a headless env. as it's something I've struggled with it in the past (and present).

[rdmueller]

added phantomjs as webdriver - I am curious if this will run in your headless environment...