Optimize network traffic by moving to odata=nometadata whenever possible

[jansenbe]

Today we've code that depends on the metadata being present (e.g. ProcessSpecialRestFieldType in JsonMappingHelper). For the majority of requests nomedata would work as well and this is something that we should consider doing to further optimize performance. Main work items for this one would be:

• Change REST client default to use nometadata
• Have optional support for still using metadata for the place where we require it + leave things as is for "external" API calls as - otherwise we'd break applications using the SDK
• Fix the base class REST payload generation and result deserialization
• Review all places where we issue REST calls and do the same
• Test, test and test...given we have 83% unit test coverage I'm quite confident that all REST calls are covered in one ore more tests, so being able to successfully run tests means we're not breaking folks.
• All test cases have to be checked in with new offline data ==> maybe best to combine with Implement requesting and handling response compression + switch to model where single request batches perform a direct call versus calling the batch endpoint #654 as that also has this requirement

Combining response compression with this will have a significant impact on the amount of data transferred.

[jansenbe]

Working on this

[jansenbe]

done