Detect branch being built with TravisCI and and use different gulp parameters depending on where the deployment is going.

build.sh

#!/usr/bin/env bash

branch=`echo ${TRAVIS_BRANCH}`;

if [ $branch = "master" ]; then
  echo "Building assets for production.";
  gulp build --env production;
else
  echo "Building assets for development.";
  gulp build --no-watch;
fi