feat(Windows): Adds Windows support to react-native-video

This PR adds react-native-windows support to react-native-video.  The Video component is implemented with a XAML MediaPlayerElement.  Most of the features implemented by Android (and some additional ones) are implemented by Windows.

Known issues and missing features include:
* onReadyForDisplay event
* local URI convention (e.g., "broadchurch" in examples changed to require("./broadchurch.mp4")
* `playableDuration` in `onVideoProgress` event is always 0.0
* `playInBackground` is not yet supported
* Volume settings are applied, but the UWP control does not handle it properly

example/windows/VideoPlayer/Properties/AssemblyInfo.cs

@@ -0,0 +1,29 @@
+using System.Reflection;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+// General Information about an assembly is controlled through the following 
+// set of attributes. Change these attribute values to modify the information
+// associated with an assembly.
+[assembly: AssemblyTitle("VideoPlayer")]
+[assembly: AssemblyDescription("")]
+[assembly: AssemblyConfiguration("")]
+[assembly: AssemblyCompany("")]
+[assembly: AssemblyProduct("VideoPlayer")]
+[assembly: AssemblyCopyright("Copyright ©  2016")]
+[assembly: AssemblyTrademark("")]
+[assembly: AssemblyCulture("")]
+
+// Version information for an assembly consists of the following four values:
+//
+//      Major Version
+//      Minor Version 
+//      Build Number
+//      Revision
+//
+// You can specify all the values or you can default the Build and Revision Numbers 
+// by using the '*' as shown below:
+// [assembly: AssemblyVersion("1.0.*")]
+[assembly: AssemblyVersion("1.0.0.0")]
+[assembly: AssemblyFileVersion("1.0.0.0")]
+[assembly: ComVisible(false)]

example/windows/VideoPlayer/Properties/Default.rd.xml

@@ -0,0 +1,31 @@
+<!--
+    This file contains Runtime Directives used by .NET Native. The defaults here are suitable for most
+    developers. However, you can modify these parameters to modify the behavior of the .NET Native
+    optimizer.
+
+    Runtime Directives are documented at http://go.microsoft.com/fwlink/?LinkID=391919
+
+    To fully enable reflection for VideoPlayer.MyClass and all of its public/private members
+    <Type Name="VideoPlayer.MyClass" Dynamic="Required All"/>
+
+    To enable dynamic creation of the specific instantiation of AppClass<T> over System.Int32
+    <TypeInstantiation Name="VideoPlayer.AppClass" Arguments="System.Int32" Activate="Required Public" />
+
+    Using the Namespace directive to apply reflection policy to all the types in a particular namespace
+    <Namespace Name="DataClasses.ViewModels" Seralize="All" />
+-->
+
+<Directives xmlns="http://schemas.microsoft.com/netfx/2013/01/metadata">
+  <Application>
+    <!--
+      An Assembly element with Name="*Application*" applies to all assemblies in
+      the application package. The asterisks are not wildcards.
+    -->
+    <Assembly Name="*Application*" Dynamic="Required All" />
+    
+    
+    <!-- Add your application specific runtime directives here. -->
+
+
+  </Application>
+</Directives>