Fix test runsettings detection

Author: networkfusion

Tests/Aws.IoTCore.Devices.UnitTests.nfproj

@@ -25,6 +25,9 @@
     <RestoreLockedMode Condition="'$(TF_BUILD)' == 'True' or '$(ContinuousIntegrationBuild)' == 'True'">true</RestoreLockedMode>
   </PropertyGroup>
   <Import Project="$(NanoFrameworkProjectSystemPath)NFProjectSystem.props" Condition="Exists('$(NanoFrameworkProjectSystemPath)NFProjectSystem.props')" />
+  <PropertyGroup>
+    <RunSettingsFilePath>$(MSBuildProjectDirectory)\nano.runsettings</RunSettingsFilePath>
+  </PropertyGroup>
   <ItemGroup>
     <Compile Include="ShadowTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />