Update travis to use container-based builds.
Update travis to use container-based builds.

akatsoulas/mozillians,anistark/mozillians,mozilla/mozillians,johngian/mozillians,brian-yang/mozillians,akarki15/mozillians,anistark/mozillians,akarki15/mozillians,akatsoulas/mozillians,akatsoulas/mozillians,mozilla/mozillians,fxa90id/mozillians,brian-yang/mozillians,safwanrahman/mozillians,brian-yang/mozillians,mozilla/mozillians,johngian/mozillians,safwanrahman/mozillians,brian-yang/mozillians,fxa90id/mozillians,safwanrahman/mozillians,chirilo/mozillians,akarki15/mozillians,fxa90id/mozillians,mozilla/mozillians,johngian/mozillians,chirilo/mozillians,johngian/mozillians,chirilo/mozillians,anistark/mozillians,anistark/mozillians,akatsoulas/mozillians,chirilo/mozillians,akarki15/mozillians,fxa90id/mozillians,safwanrahman/mozillians