Update all NuGet references to their latest versions

James, I've updated all the NuGet packages in the solution and updated the nuspec file to address issue #7.  I didn't change the version number, however, because I figure that's up to you ;)

Also, sorry about the huge number of changes.  A few of the package updates (WebAPI specifically) added a whole lot to the help section of the Web API sample.  The core library didn't require any changes other than updating the the actual references and removing a reference to the GAC version of System.Data.Services.Client.  This library seems to be duplicated by Microsoft.Data.Services.Client and I was getting ambiguous reference errors on build.

Let me know if this doesn't work for you!