travis: sphinx does not support python 2.6 anymore (#2485)
travis: sphinx does not support python 2.6 anymore (#2485)


lgarren/spack,matthiasdiener/spack,mfherbst/spack,lgarren/spack,mfherbst/spack,krafczyk/spack,tmerrick1/spack,skosukhin/spack,matthiasdiener/spack,tmerrick1/spack,TheTimmy/spack,skosukhin/spack,lgarren/spack,LLNL/spack,EmreAtes/spack,TheTimmy/spack,lgarren/spack,tmerrick1/spack,iulian787/spack,skosukhin/spack,tmerrick1/spack,skosukhin/spack,TheTimmy/spack,TheTimmy/spack,matthiasdiener/spack,LLNL/spack,iulian787/spack,iulian787/spack,LLNL/spack,LLNL/spack,LLNL/spack,lgarren/spack,EmreAtes/spack,mfherbst/spack,TheTimmy/spack,krafczyk/spack,krafczyk/spack,EmreAtes/spack,iulian787/spack,iulian787/spack,EmreAtes/spack,krafczyk/spack,krafczyk/spack,matthiasdiener/spack,matthiasdiener/spack,tmerrick1/spack,EmreAtes/spack,mfherbst/spack,skosukhin/spack,mfherbst/spack