change scope of cluster fixture to session
change scope of cluster fixture to session

after splitting out the test into multiple modules,
this should be session scoped as to share apps
between tests

xinxian0458/dcos,amitaekbote/dcos,amitaekbote/dcos,mesosphere-mergebot/dcos,jeid64/dcos,lingmann/dcos,mnaboka/dcos,surdy/dcos,xinxian0458/dcos,dcos/dcos,GoelDeepak/dcos,asridharan/dcos,mesosphere-mergebot/dcos,kensipe/dcos,asridharan/dcos,jeid64/dcos,darkonie/dcos,mesosphere-mergebot/dcos,mnaboka/dcos,mesosphere-mergebot/mergebot-test-dcos,surdy/dcos,mesosphere-mergebot/mergebot-test-dcos,vishnu2kmohan/dcos,dcos/dcos,mellenburg/dcos,mellenburg/dcos,mnaboka/dcos,GoelDeepak/dcos,darkonie/dcos,mesosphere-mergebot/dcos,BenWhitehead/dcos,vishnu2kmohan/dcos,GoelDeepak/dcos,darkonie/dcos,dcos/dcos,branden/dcos,mesosphere-mergebot/mergebot-test-dcos,darkonie/dcos,dcos/dcos,surdy/dcos,vishnu2kmohan/dcos,GoelDeepak/dcos,amitaekbote/dcos,vishnu2kmohan/dcos,mnaboka/dcos,branden/dcos,surdy/dcos,jeid64/dcos,BenWhitehead/dcos,kensipe/dcos,kensipe/dcos,lingmann/dcos,kensipe/dcos,darkonie/dcos,mnaboka/dcos,branden/dcos,mellenburg/dcos,lingmann/dcos,asridharan/dcos,amitaekbote/dcos,xinxian0458/dcos,BenWhitehead/dcos,jeid64/dcos,asridharan/dcos,branden/dcos,mesosphere-mergebot/mergebot-test-dcos,mellenburg/dcos,BenWhitehead/dcos,xinxian0458/dcos,dcos/dcos,lingmann/dcos