Webapi-Swagger : Apply Global consumes and produces MIME types and support for overriding them

[kahlil29]

For the global consumes and produces present in _swaggerConsumes and _swaggerProduces respectively, we need to consider these types and set the types in the Contract correctly.

consumes -> RequestBody (in Contract)
produces -> ContentTypes (in Contract)

Also, in case any MIME Types are specified in the "local" definitions for Operations, we need to disregard the global values and only consider these locally defined MIME Types for that particular Operation.