[0.21.0] Bump version numbers

Revert "Move `react` to peerDependencies"

This reverts commit 9f01f96.

[0.20.0] Bump version numbers

master and latest

version 0.20.0-rc1

[0.20.0-rc] Bump version numbers

[0.19.0] Bump version numbers

[0.19.0-rc] Bump version numbers

Revert "Dont call npm before node is available"

This reverts commit 7ecb693.

This breaks Xcode build, see discussion on facebook#5156

[0.18.0-rc] Bump version numbers