Add folder for local packages

Rx.NET/Integration/LocalPackages/.keepme

@@ -0,0 +1 @@
+Placeholder to keep this directory

Rx.NET/Integration/NuGet.Config

@@ -1,9 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
 <configuration>
-  <packageSources>    
-    <add key="AppVeyor (CI) rxnet" value="https://ci.appveyor.com/nuget/rx-net-ljfp6fos5bxs" />
+  <packageSources>
     <add key="myget.org rxnet" value="https://dotnet.myget.org/F/rx/api/v3/index.json" />
     <add key="Build Packages" value="https://www.myget.org/F/c037199d-41df-4567-b966-25ff65324688/api/v3/index.json" />
-    <add key="NuGet.org" value="https://api.nuget.org/v3/index.json" />        
+    <add key="NuGet.org" value="https://api.nuget.org/v3/index.json" />
+    <add key="Local Packages" value=".\LocalPackages" />
   </packageSources>  
 </configuration>