Remove NetStandardLibraryImplicitPackageVersion (#396)

- For consistency with other repos

build/common.props

@@ -18,7 +18,7 @@
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)'=='.NETFramework' AND '$(OutputType)'=='library'">
-    <PackageReference Include="NETStandard.Library" Version="$(NETStandardLibraryImplicitPackageVersion)" />
+    <PackageReference Include="NETStandard.Library" Version="$(NETStandardImplicitPackageVersion)" />
   </ItemGroup>
 
 </Project>

build/dependencies.props

@@ -6,7 +6,6 @@
     <InternalAspNetCoreSdkVersion>2.0.1-*</InternalAspNetCoreSdkVersion>
     <MoqVersion>4.7.49</MoqVersion>
     <NETStandardImplicitPackageVersion>2.0.0-*</NETStandardImplicitPackageVersion>
-    <NETStandardLibraryImplicitPackageVersion>2.0.0-*</NETStandardLibraryImplicitPackageVersion>
     <NETStandardLibraryNETFrameworkVersion>2.0.0-*</NETStandardLibraryNETFrameworkVersion>
     <RuntimeFrameworkVersion Condition="'$(TargetFramework)'=='netcoreapp2.0'">2.0.0-*</RuntimeFrameworkVersion>
     <TestSdkVersion>15.3.0-*</TestSdkVersion>