Fix build

Author: Jonas Pyfferoen

src/Our.Umbraco.DocTypeGridEditor/Our.Umbraco.DocTypeGridEditor.csproj

@@ -72,7 +72,8 @@
     <Reference Include="System.Core" />
     <Reference Include="System.Net.Http" />
     <Reference Include="System.Net.Http.Formatting, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
-      <Private>False</Private>
+      <SpecificVersion>False</SpecificVersion>
+      <HintPath>..\packages\Microsoft.AspNet.WebApi.Client.5.2.3\lib\net45\System.Net.Http.Formatting.dll</HintPath>
     </Reference>
     <Reference Include="System.Web" />
     <Reference Include="System.Web.Http, Version=5.2.3.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">