travis: disable custom version of firefox as it is failing to download
travis: disable custom version of firefox as it is failing to download

CIRANDAS/noosfero-ecosol,vfcosta/noosfero,vfcosta/noosfero,vfcosta/noosfero,vfcosta/noosfero,CIRANDAS/noosfero-ecosol,vfcosta/noosfero,CIRANDAS/noosfero-ecosol,CIRANDAS/noosfero-ecosol,CIRANDAS/noosfero-ecosol,vfcosta/noosfero