Improve the default client loading code. (#251)

* Improve the default client loading code.

* Address comments.

src/KubernetesClient/KubernetesClientConfiguration.ConfigFile.cs

@@ -24,6 +24,26 @@ namespace k8s
         /// </summary>
         public string CurrentContext { get; private set; }
 
+        /// <summary>
+        ///     Initializes a new instance of the <see cref="KubernetesClientConfiguration" /> from config file
+        /// </summary>
+        public static KubernetesClientConfiguration BuildDefaultConfig() {
+            var kubeconfig = Environment.GetEnvironmentVariable("KUBECONFIG");
+            if (kubeconfig != null) {
+                return BuildConfigFromConfigFile(kubeconfigPath: kubeconfig);
+            }
+            if (File.Exists(KubeConfigDefaultLocation)) {
+                return BuildConfigFromConfigFile(kubeconfigPath: KubeConfigDefaultLocation);
+            }
+            if (IsInCluster()) {
+                return InClusterConfig();
+            }
+            var config = new KubernetesClientConfiguration();
+            config.Host = "http://localhost:8080";
+            return config;
+        }
+
+
         /// <summary>
         ///     Initializes a new instance of the <see cref="KubernetesClientConfiguration" /> from config file
         /// </summary>