Issue 138: FSharp.Core references, plus fix up a prompt on Dapper.Contrib.Tests

System.XML references were already added in f6e29fecd549dbaae76437f0351b5b2b7409d18a, so this just adds the FSharp.Core reference and libraries.

Also added prompt to the Dapper.Contrib.Tests runner so that it is consistent with the other test projects