[REEF-1857] Add netcoreapp2.0 and netstandard2.0 to same projects

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

JIRA: [REEF-1857](https://issues.apache.org/jira/browse/REEF-1857)

Pull request:
  This closes #1357
diff --git a/lang/cs/Org.Apache.REEF.Common/Org.Apache.REEF.Common.DotNet.csproj b/lang/cs/Org.Apache.REEF.Common/Org.Apache.REEF.Common.DotNet.csproj
index 0847bf0..396a6d3 100644
--- a/lang/cs/Org.Apache.REEF.Common/Org.Apache.REEF.Common.DotNet.csproj
+++ b/lang/cs/Org.Apache.REEF.Common/Org.Apache.REEF.Common.DotNet.csproj
@@ -21,7 +21,7 @@
     <AssemblyName>Org.Apache.REEF.Common</AssemblyName>
     <Description>REEF Common Infrastructure</Description>
     <PackageTags>REEF Common Infrastructure</PackageTags>
-    <TargetFrameworks>net46;net451</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;netcoreapp2.0;net46;net451</TargetFrameworks>
   </PropertyGroup>
   <Import Project="..\build.DotNet.props" />
   <ItemGroup>
diff --git a/lang/cs/Org.Apache.REEF.Driver/Org.Apache.REEF.Driver.DotNet.csproj b/lang/cs/Org.Apache.REEF.Driver/Org.Apache.REEF.Driver.DotNet.csproj
index 8c38e10..2cd7d84 100644
--- a/lang/cs/Org.Apache.REEF.Driver/Org.Apache.REEF.Driver.DotNet.csproj
+++ b/lang/cs/Org.Apache.REEF.Driver/Org.Apache.REEF.Driver.DotNet.csproj
@@ -21,7 +21,7 @@
     <AssemblyName>Org.Apache.REEF.Driver</AssemblyName>
     <Description>Driver for REEF.NET</Description>
     <PackageTags>REEF Driver</PackageTags>
-    <TargetFrameworks>net46;net451</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;netcoreapp2.0;net46;net451</TargetFrameworks>
   </PropertyGroup>
   <Import Project="..\build.DotNet.props" />
   <ItemGroup>
diff --git a/lang/cs/Org.Apache.REEF.Evaluator/Org.Apache.REEF.Evaluator.DotNet.csproj b/lang/cs/Org.Apache.REEF.Evaluator/Org.Apache.REEF.Evaluator.DotNet.csproj
index 4537023..28e1c2f 100644
--- a/lang/cs/Org.Apache.REEF.Evaluator/Org.Apache.REEF.Evaluator.DotNet.csproj
+++ b/lang/cs/Org.Apache.REEF.Evaluator/Org.Apache.REEF.Evaluator.DotNet.csproj
@@ -21,7 +21,7 @@
     <AssemblyName>Org.Apache.REEF.Evaluator</AssemblyName>
     <Description>Evaluator for REEF.NET</Description>
     <PackageTags>REEF Evaluator</PackageTags>
-    <TargetFrameworks>net46;net451</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;netcoreapp2.0;net46;net451</TargetFrameworks>
   </PropertyGroup>
   <Import Project="..\build.DotNet.props" />
   <ItemGroup>
diff --git a/lang/cs/Org.Apache.REEF.Tang/Org.Apache.REEF.Tang.DotNet.csproj b/lang/cs/Org.Apache.REEF.Tang/Org.Apache.REEF.Tang.DotNet.csproj
index 9ae0cf3..d745fba 100644
--- a/lang/cs/Org.Apache.REEF.Tang/Org.Apache.REEF.Tang.DotNet.csproj
+++ b/lang/cs/Org.Apache.REEF.Tang/Org.Apache.REEF.Tang.DotNet.csproj
@@ -21,7 +21,7 @@
     <AssemblyName>Org.Apache.REEF.Tang</AssemblyName>
     <Description>Tang is a dependency injection framework</Description>
     <PackageTags> Apache REEF tang dependency injection</PackageTags>
-    <TargetFrameworks>net46;net451</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;netcoreapp2.0;net46;net451</TargetFrameworks>
   </PropertyGroup>
   <Import Project="..\build.DotNet.props" />
   <ItemGroup>
diff --git a/lang/cs/Org.Apache.REEF.Wake.Tests/Org.Apache.REEF.Wake.Tests.DotNet.csproj b/lang/cs/Org.Apache.REEF.Wake.Tests/Org.Apache.REEF.Wake.Tests.DotNet.csproj
index fb96f88..f75962e 100644
--- a/lang/cs/Org.Apache.REEF.Wake.Tests/Org.Apache.REEF.Wake.Tests.DotNet.csproj
+++ b/lang/cs/Org.Apache.REEF.Wake.Tests/Org.Apache.REEF.Wake.Tests.DotNet.csproj
@@ -17,7 +17,7 @@
 -->
   <PropertyGroup>
     <AssemblyName>Org.Apache.REEF.Wake.Tests</AssemblyName>
-    <TargetFrameworks>net46;net451</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;netcoreapp2.0;net46;net451</TargetFrameworks>
   </PropertyGroup>
   <Import Project="..\build.DotNet.props" />
   <ItemGroup>
diff --git a/lang/cs/Org.Apache.REEF.Wake/Org.Apache.REEF.Wake.DotNet.csproj b/lang/cs/Org.Apache.REEF.Wake/Org.Apache.REEF.Wake.DotNet.csproj
index 1028bb7..b2f59d5 100644
--- a/lang/cs/Org.Apache.REEF.Wake/Org.Apache.REEF.Wake.DotNet.csproj
+++ b/lang/cs/Org.Apache.REEF.Wake/Org.Apache.REEF.Wake.DotNet.csproj
@@ -19,7 +19,7 @@
     <AssemblyName>Org.Apache.REEF.Wake</AssemblyName>
     <Description>Wake is an event-driven framework</Description>
     <PackageTags>wake event-driven</PackageTags>
-    <TargetFrameworks>net46;net451</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;netcoreapp2.0;net46;net451</TargetFrameworks>
   </PropertyGroup>
   <Import Project="..\build.DotNet.props" />
   <ItemGroup>