Fix strong name keyfile

Generated new nunit.snk, updated NAnt to use the snk file in the updated location and update the nunitlite projects to be signed since they are built signed by NAnt and I think Visual Studio should produce the same results as NAnt.

Updated the nunitlite projects for Silverlight, NETCF 2.0 and NETCF 3.0. I have built but not tested Silverlight. I have not built or tested CF.