can't import es6modules that have a single component

[catmando]

If an es6 module has a single component (and its set to the default for the module) we don't automatically import it.

Fix is to add this check in ReactWrapper.eval_native_component

component = `component.default` if `component.__esModule` 

workaround is to either use the import directive in the manifest (which takes care of this case) or do a require('foo').default

see for details
https://stackoverflow.com/questions/40294870/module-exports-vs-export-default-in-node-js-and-es6