Fix support for .NET 4.0 and .NET 4.5.

Author: Athari

CommandLine.nuspec

@@ -30,6 +30,8 @@
         <dependency id="System.Runtime" version="4.1.0-rc2-24027" />
         <dependency id="System.Runtime.Extensions" version="4.1.0-rc2-24027" />
       </group>
+      <group targetFramework=".NETFramework4.0" />
+      <group targetFramework=".NETFramework4.5" />
     </dependencies>
   </metadata>
   <files>