updates to travis ci config for yarn.
updates to travis ci config for yarn.

aaronholmes/yelp-clone,danpersa/remindmetolive-react,lisavogtsf/canned-react-slingshot-app,coryhouse/react-slingshot,garusis/up-designer,git-okuzenko/react-redux,danpersa/remindmetolive-react,MouseZero/nightlife-frontend,flibertigibet/react-redux-starter-kit-custom,kpuno/survey-app,kpuno/survey-app,oshalygin/react-slingshot,AurimasSk/DemoStore,lisavogtsf/canned-react-slingshot-app,barbel840113/testapp,oshalygin/react-slingshot,AurimasSk/DemoStore,MouseZero/nightlife-frontend,svitekpavel/Conway-s-Game-of-Life,svitekpavel/Conway-s-Game-of-Life,danpersa/remindmetolive-react,aaronholmes/yelp-clone,BenMGilman/react-lunch-and-learn,coryhouse/react-slingshot,barbel840113/testapp,git-okuzenko/react-redux,flibertigibet/react-redux-starter-kit-custom,garusis/up-designer,BenMGilman/react-lunch-and-learn