When creating DropboxClient I'm getting an unable to find System.Net.Http, Version=4.0.0.0 assembly

https://github.com/BMurri/WinPass

Project to run is "KeePass" within the solution.

Error is thrown in KeePass\Sources\DropBox\DropBoxUtils.cs line 12.

Exact same error is thrown using real devices running Windows Mobile 10 and emulators running Windows Phone 8.1.

System.IO.FileNotFoundException
Could not load file or assembly 'System.Net.Http, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.
Stack Trace: at Dropbox.Api.DropboxRequestHandlerOptions..ctor(DropboxClientConfig config, Stringoauth2AccessToken)
at Dropbox.Api.DropboxClient..ctor(String oauth2AccessToken, DropboxClientConfig config)
at KeePass.Sources.DropBox.List.RefreshList()
at KeePass.Sources.DropBox.List.OnNavigatedTo(Boolean cancelled, NavigationEventArgs e)
at KeePass.Utils.KeePassPage.OnNavigatedTo(NavigationEventArgs e) at Microsoft.Phone.Controls.PhoneApplicationPage.InternalOnNavigatedTo(NavigationEventArgs e) at Microsoft.Phone.Controls.PhoneApplicationPage.Microsoft.Phone.Controls.IPhoneApplicationPage.InternalOnNavigatedToX(NavigationEventArgs e) at System.Windows.Navigation.NavigationService.RaiseNavigated(Object content, Uri uri, NavigationMode mode, Boolean isNavigationInitiator, IPhoneApplicationPage existingContentPage, IPhoneApplicationPage newContentPage) at System.Windows.Navigation.NavigationService.Journal_NavigatedExternally(Object sender, JournalEventArgs args) at System.Windows.Navigation.Journal.OnNavigatedExternally(String name, Uri uri, NavigationMode mode) at System.Windows.Navigation.Journal.DoExternalNavigation(NavigationDirection direction, Boolean isResumeActivation, Boolean isRefresh) at System.Windows.Navigation.Journal.NavigateTo(NavigationDirection direction, Boolean isResumeActivation) at Microsoft.Phone.TaskModel.Interop.Task.FireOnNavigateTo(Int32 direction, BooleanisResumeActivation)Uri: /Sources/DropBox/List.xaml?token=****************