Add release branches to travis testing.
Add release branches to travis testing.

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