Normally, after a code change to react-native-sortable-listview src files,
you must remove the node_modules/react-native-sortable-listview directory
and npm install. The react-native packager wont follow symlinks.
To assist development, instead of npm run start, use:
npm run refresh
This will remove the node_modules/react-native-sortable-listview directory,
copy the react-native-sortable-listview src files from .. and start the
packager. Since the packager won't notice changes in node_modules,
each time you make a change in the src files, you will need to
manually kill the packager with ^C, then just rerun npm run refresh