added xml validate file
added xml validate file

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