Add initial welcome page

.flowconfig

app/features/app/components/App.js

app/features/conference/components/Conference.js

app/features/conference/index.js

app/features/conference/styled/Wrapper.js

app/features/conference/styled/index.js

app/features/welcome/components/Welcome.js

app/features/welcome/components/index.js

app/features/welcome/index.js

app/features/welcome/styled/Content.js

app/features/welcome/styled/Form.js

app/features/welcome/styled/WelcomeWrapper.js

app/features/welcome/styled/index.js

app/index.html

app/index.js

package-lock.json

package.json

webpack.config.js