Removed 'nucmd work run' command

Since separating the work service in to it's own repository, this command's usefulness has diminished dramatically. All it does is make nucmd dependent on the Work Service Package, and thus requires you to remember to update that package in NuCmd before you can run any jobs. Instead, there is a JobHost.exe app in the NuGet.Services.Work repo that allows you to easily run work service jobs.