travis config: only run on pull requests and master
travis config: only run on pull requests and master

alphagov/trade-tariff-admin,bitzesty/trade-tariff-admin,alphagov/trade-tariff-admin,alphagov/trade-tariff-admin,alphagov/trade-tariff-admin,bitzesty/trade-tariff-admin,bitzesty/trade-tariff-admin,bitzesty/trade-tariff-admin