Summary:
* This allows `react-native` to work for users on fedora.
* `react-native run-android` was failing because the launch packager script was unable to find packager.sh (see `source` in `man bash`).
* This change sets cwd for the dev server when run with `run-android`.
Closes https://github.com/facebook/react-native/pull/7316
Differential Revision: D3255866
fb-gh-sync-id: 88f6b18f7c61636ce8fecef77f7f4e60b1d9a637
fbshipit-source-id: 88f6b18f7c61636ce8fecef77f7f4e60b1d9a637