Changed xvfb-run to use a different server number if the current one is taken.
Changed xvfb-run to use a different server number if the current one is taken.

phac-nml/irida,phac-nml/irida,phac-nml/irida,phac-nml/irida,phac-nml/irida,phac-nml/irida,phac-nml/irida,phac-nml/irida