CORS support for V2 Northwind

[boghyon]

Same as #29, but this issue is about enabling CORS for the V2 Northwind service as it's still one of the most popular OData services used for tutorials and demos.

Sample: https://embed.plnkr.co/ke8FKULI3ruG5qlM?show=manifest.json,preview:?sap-ui-xx-componentPreload=off
The above plunk should display a list of items if CORS is enabled.

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In response to @mikepizzo #29 (comment)

[boghyon]

Hi @mikepizzo, there are still many enterprise applications that leverage OData V2 services. For demo, tutorials, and bug reports, it would be nice if at least the V2 Northwind service could support CORS - like the V4 TripPin already does thanks to #29