added fix to IncidentNeutron.from_hdf5() for Python 2
added fix to IncidentNeutron.from_hdf5() for Python 2

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