Fully customisable serialisation with contract resolvers

[jordangray]

Provide a mechanism akin to Json.NET's custom contract resolvers, allowing users to fully customise serialisation according to their needs.

Example use case

A reporting tool that allows users to determine, on a per-report basis, what columns should be present in the generated Excel document.

(As suggested by Marcus Diamond.)

[jordangray]

Update: a very preliminary version of this is available at https://github.com/jordangray/WebApiContrib.Formatting.Xlsx. I'll soon merge this to a dev branch for people who want early access while the feature is being reviewed/developed. Feedback welcome!

[jordangray]

This is now handled with the IColumnResolver and IXlsxSerialiser interfaces added in #47; default implementations of both are provided to build upon. You'll be able to get this soon on NuGet as 2.0.0-pre, or you can grab it now in the pre branch.