I am unable to install xamarine packages in vs17 from Nuget
                            
                         
                        
                     
                 
                
                    
Error        Could not install package 'Xamarin.Android.Support.v4 27.0.2.1'. You are trying to install this package into a project that targets '.NETFramework,Version=v4.6', but the package does not contain any assembly references or content files that are compatible with that framework. For more information, contact the package author.