Fix .travis.yml
Fix .travis.yml

samuelshaner/openmc,bhermanmit/openmc,paulromano/openmc,samuelshaner/openmc,samuelshaner/openmc,shikhar413/openmc,walshjon/openmc,shikhar413/openmc,amandalund/openmc,amandalund/openmc,wbinventor/openmc,smharper/openmc,walshjon/openmc,liangjg/openmc,smharper/openmc,bhermanmit/openmc,mit-crpg/openmc,amandalund/openmc,liangjg/openmc,wbinventor/openmc,paulromano/openmc,samuelshaner/openmc,johnnyliu27/openmc,johnnyliu27/openmc,smharper/openmc,mit-crpg/openmc,amandalund/openmc,wbinventor/openmc,paulromano/openmc,johnnyliu27/openmc,shikhar413/openmc,liangjg/openmc,walshjon/openmc,shikhar413/openmc,mit-crpg/openmc,mit-crpg/openmc,liangjg/openmc,smharper/openmc,walshjon/openmc,johnnyliu27/openmc,paulromano/openmc,wbinventor/openmc