Setup travis
Note
View travis-ci official deployment guide: Link
1. Generate firebase token.
# This generates a token, e.g. "1/AD7sdasdasdKJA824OvEFc1c89Xz2ilBlaBlaBla"
firebase login:ci
# Encrypt this token
travis encrypt "1/AD7sdasdasdKJA824OvEFc1c89Xz2ilBlaBlaBla" --add
# This command may generate a warning ("If you tried to pass the name of the repository as the first argument, you probably won't get the results you wanted"). You can ignore it.