add jinja2 req to travis (for astropy dev)
add jinja2 req to travis (for astropy dev)

kbarbary/sncosmo,kbarbary/sncosmo,sncosmo/sncosmo,kbarbary/sncosmo,dannygoldstein/sncosmo,dannygoldstein/sncosmo,dannygoldstein/sncosmo,sncosmo/sncosmo,sncosmo/sncosmo