fix(NuGet): align NuGet dependencies with react-native-windows (#1209)

Switching to .csproj-based NuGet package references and updating to match the current dependencies for react-native-windows.

Towards microsoft/react-native-windows#1644

windows/CodePush.Net46/CodePush.Net46.csproj

@@ -86,12 +86,11 @@
     <None Include="packages.config" />
   </ItemGroup>
   <ItemGroup>
-	<ProjectReference Include="..\..\react-native-windows\ReactWindows\ReactNative.Net46\ReactNative.Net46.csproj">
+    <ProjectReference Include="..\..\..\react-native-windows\ReactWindows\ReactNative.Net46\ReactNative.Net46.csproj">
       <Project>{22cbff9c-fe36-43e8-a246-266c7635e662}</Project>
       <Name>ReactNative.Net46</Name>
     </ProjectReference>
   </ItemGroup>
-  <ItemGroup />
   <Import Project="..\CodePush.Shared\CodePush.Shared.projitems" Label="Shared" />
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 

windows/CodePush/CodePush.csproj

@@ -83,10 +83,9 @@
     <UseVSHostingProcess>false</UseVSHostingProcess>
     <ErrorReport>prompt</ErrorReport>
   </PropertyGroup>
-  <ItemGroup>
-    <!-- A reference to the entire .Net Framework and Windows SDK are automatically included -->
-    <None Include="project.json" />
-  </ItemGroup>
+  <PropertyGroup>
+    <RestoreProjectStyle>PackageReference</RestoreProjectStyle>
+  </PropertyGroup>
   <ItemGroup>
     <Compile Include="UpdateManager.cs" />
     <Compile Include="UpdateUtils.cs" />
@@ -101,11 +100,19 @@
     </SDKReference>
   </ItemGroup>
   <ItemGroup>
-    <ProjectReference Include="..\..\react-native-windows\ReactWindows\ReactNative\ReactNative.csproj">
+    <ProjectReference Include="..\..\..\react-native-windows\ReactWindows\ReactNative\ReactNative.csproj">
       <Project>{c7673ad5-e3aa-468c-a5fd-fa38154e205c}</Project>
       <Name>ReactNative</Name>
     </ProjectReference>
   </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="Newtonsoft.Json">
+      <Version>10.0.3</Version>
+    </PackageReference>
+    <PackageReference Include="Microsoft.NETCore.UniversalWindowsPlatform">
+      <Version>6.0.6</Version>
+    </PackageReference>
+  </ItemGroup>
   <Import Project="..\CodePush.Shared\CodePush.Shared.projitems" Label="Shared" />
   <PropertyGroup Condition=" '$(VisualStudioVersion)' == '' or '$(VisualStudioVersion)' &lt; '14.0' ">
     <VisualStudioVersion>14.0</VisualStudioVersion>