Clear Nuget.Config (#80)

Author: dingmeng-xue

Diff for: vscode-extension/server/NuGet.Config

@@ -4,7 +4,11 @@
     <add key="disableSourceControlIntegration" value="true" />
   </solution>
   <packageSources>
-    <add key="omnisharp" value="https://www.myget.org/F/omnisharp/api/v3/index.json" protocolVersion="3" />
+    <clear/>
+    <!-- Do not add any additional feeds if new packages are needed they need to come from nuget.org or our azure-sdk-for-net DevOps feed -->
     <add key="nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
   </packageSources>
+  <disabledPackageSources>
+    <clear />
+  </disabledPackageSources>
 </configuration>