Update android appicons

Update screenshot

Adjust intro image placement

Update appicon size

Minor edit

Update readme.md

Update readme.md

Update readme.md

Refactor code

Add to Jest setup, and start basic component tests

Upgrade react-native-onboarding-swiper

Update package and yarn

Add flow-bin and babel-preset-flow and npm flow script

Add readme.md

Re-style CryptoGlobal