public PackageChooserViewModel(IMruPackageSourceManager packageSourceManager)
{
Packages = new ObservableCollection<PackageInfo>();
NavigationCommand = new NavigateCommand(this);
SortCommand = new RelayCommand<string>(Sort, column => TotalPackageCount > 0);
SearchCommand = new RelayCommand<string>(Search);
LoadedCommand = new RelayCommand(() => Sort("VersionDownloadCount", ListSortDirection.Descending));
ChangePackageSourceCommand = new RelayCommand<string>(ChangePackageSource);
_credentialProvider = new AutoDiscoverCredentialProvider();
_proxyService = new ProxyService(_credentialProvider);
_packageSourceManager = packageSourceManager;
}