CI: Upgrade Travis GCC for C++14 support
CI: Upgrade Travis GCC for C++14 support

kaspermarstal/SuperElastix,SuperElastix/SuperElastix,SuperElastix/SuperElastix,kaspermarstal/SuperElastix,SuperElastix/SuperElastix,SuperElastix/SuperElastix,kaspermarstal/SuperElastix