Merge pull request #51 from nul800sebastiaan/issue50

GetFiles shouldn't return a list of null #50

Author: JimBobSquarePants

src/UmbracoFileSystemProviders.Azure/AzureFileSystem.cs

@@ -429,7 +429,7 @@ public IEnumerable<string> GetFiles(string path, string filter)
                     }
 
                     return null;
-                });
+                }).Where(x => x != null);
         }
 
         /// <summary>