fix: lazy load getRandomValues (#537)
fix: lazy load getRandomValues (#537)

Without this change, React Native projects must manage an implicit
dependency on `react-native-get-random-values`, and try to ensure that
it gets loaded before `uuid` does.

With this change, the React Native polyfill simply needs to be installed
sometime before the first uuid is created.

Fixes #536
kelektiv/node-uuid