Two tweaks to fix two navigational crashes in Android.

[robintschroeder]

1) Navigating to the About page

Xamarin.Forms.Xaml.XamlParseException: Position 9:14. StaticResource not found for key ColorAppBackground StaticResourceExtension.GetApplicationLevelResource (System.String key, System.Xml.IXmlLineInfo xmlLineInfo) StaticResourceExtension.ProvideValue (System.IServiceProvider serviceProvider) IndexPage.InitializeComponent () Xappy.About.IndexPage..ctor () [0x00008] in :0 (wrapper managed-to-native) System.Reflection.RuntimeConstructorInfo.InternalInvoke(System.Reflection.RuntimeConstructorInfo,object,object[],System.Exception&) RuntimeConstructorInfo.InternalInvoke (System.Object obj, System.Object[] parameters, System.Boolean wrapExceptions)

2) Awaiting the closure of the settings modal

System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index List`1[T].get_Item (System.Int32 index) Application+NavigationImpl.OnPopModal (System.Boolean animated) D:\a\1\s\Xamarin.Forms.Core\Application.cs:374 SettingsPages.Handle_CloseClicked (System.Object sender, System.EventArgs e) C:\Users\RobinSchroeder\source\repos\Xappy\Xappy\Xappy\Content\Settings\SettingsPages.xaml.cs:41 AsyncMethodBuilderCore+<>c.b7_0 (System.Object state) SyncContext+<>c__DisplayClass2_0.b0 () Thread+RunnableImplementor.Run () IRunnableInvoker.n_Run (System.IntPtr jnienv, System.IntPtr native__this)

[robintschroeder]

It appears that @Depechie has a PR to fix the missing style on the about page. #42