Summary:
If installation fails, we should exit with an error code and not just a
message. This should help narrow down the CI failures, too.
Pull Request resolved: https://github.com/facebook/flipper/pull/292
Reviewed By: danielbuechele
Differential Revision: D10255759
Pulled By: passy
fbshipit-source-id: a6b033deadf11069e6c5665870a811ae2d0ec5ef