Summary: When Node is installed with nvm, scripts invoked from Xcode need to set up nvm. This can be done either by sourcing .profile/.bash_profile/.bashrc/etc... or by sourcing nvm.sh directly -- this diff does the latter and handles the case where nvm may have been installed the official way (under ~/.nvm/nvm.sh AFAIK) or via homebrew.
Closes https://github.com/facebook/react-native/pull/4015
Reviewed By: svcscm
Differential Revision: D2633301
Pulled By: frantic
fb-gh-sync-id: 3c2b9b0d21887ba21d6f85f5d279314d50c1db28