support scoped haste package names
support scoped haste package names

Summary:
npm supports "scoped packages" like `react-native/assets`. we already are adding the scoped names to the module map (they are in the package.json name field that way and just work), but we didn't support resolving them.

Changelog: [fix] Add support for scoped package names when using the Haste module resolver

Reviewed By: bradzacher

Differential Revision: D41056423

fbshipit-source-id: e7d3a635dba1bac876ae73ae5afd091bb76ce2a9

mroch/flow,mroch/flow,facebook/flow,facebook/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow,facebook/flow,facebook/flow,facebook/flow,mroch/flow,mroch/flow,mroch/flow