title: How to provide custom mediatype formats for OData Api
body: <p>I am developing an ASP.NET application that uses ODataApiController.  The application shows users a grid by querying data and showing it in a table.  I would like the ability to export to a number of different formats, including CSV and a custom XML format.  Ideally, I would just take the same OData query the grid uses, set the Accepts header, and get back CSV or XML.</p>
  
  <p>I've created MediaTypeFormatters to do what I need, but they only work with "regular" ApiController, not ODataApiController.  Looking at the code in github, I see that OData has it's own MediaTypeFormatter scheme to handle various cases, and built in XML and JSON formatters. But I can't see how to hook into this to provide custom formats.  I've attempted inheriting ODataMediaTypeFormatter, but a breakpoint set on it never hits.</p>
  
  <p>I am only really interested in output formats here.  How can I extend OdataApi to output different formats?</p>