fixed lint errors

src/actions/auth.js

src/components/App.js

src/components/Footer.js

src/components/Main.js

src/components/pages/Circles.js

src/components/pages/NotFound.js

src/components/pages/Profile.js

src/components/pages/Schedule.js

src/components/pages/Statistics.js

src/components/pages/Trainers.js

src/index.css

src/index.js