[REEF-1853] Add netcoreapp2.0 to target framework for Org.Apache.Utilities

This addressed the issue by adding netcoreapp2.0 to csproj file

JIRA:
  [REEF-1853](https://issues.apache.org/jira/browse/REEF-1853)
 
Pull request:
  This closes #1354
diff --git a/lang/cs/Org.Apache.REEF.Utilities/Org.Apache.REEF.Utilities.DotNet.csproj b/lang/cs/Org.Apache.REEF.Utilities/Org.Apache.REEF.Utilities.DotNet.csproj
index 4d2dd35..2a65732 100644
--- a/lang/cs/Org.Apache.REEF.Utilities/Org.Apache.REEF.Utilities.DotNet.csproj
+++ b/lang/cs/Org.Apache.REEF.Utilities/Org.Apache.REEF.Utilities.DotNet.csproj
@@ -19,7 +19,7 @@
     <AssemblyName>Org.Apache.REEF.Utilities</AssemblyName>
     <Description>Common utilities such as logging shared across REEF/Wake/Tang</Description>
     <PackageTags>Apache REEF REEF/Wake/Tang common utilities</PackageTags>
-    <TargetFrameworks>netstandard2.0;net46;net451</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;netcoreapp2.0;net46;net451</TargetFrameworks>
   </PropertyGroup>
   <Import Project="..\build.DotNet.props" />
   <ItemGroup>