Use the bundled NETStandard.Library package in netstandard targeting libraries

Author: pranavkm

build/dependencies.props

@@ -4,6 +4,7 @@
     <AspNetIntegrationTestingVersion>0.4.0-*</AspNetIntegrationTestingVersion>
     <AspNetCoreModuleVersion>1.0.0-*</AspNetCoreModuleVersion>
     <CoreFxVersion>4.3.0</CoreFxVersion>
+    <NETStandardImplicitPackageVersion>$(BundledNETStandardPackageVersion)</NETStandardImplicitPackageVersion>
     <TestSdkVersion>15.0.0</TestSdkVersion>
     <XunitVersion>2.2.0</XunitVersion>
   </PropertyGroup>