Add default nuget.config

nuget.config

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+    <config>
+        <add key="repositoryPath" value="%PACKAGEHOME%/External" />
+    </config>
+
+    <packageRestore>
+        <add key="enabled" value="True" />
+        <add key="automatic" value="True" />
+    </packageRestore>
+    <packageSources>
+        <add key="NuGet official package source" value="https://api.nuget.org/v3/index.json" />
+    </packageSources>
+
+    <disabledPackageSources />
+</configuration>