Adding test cases for Corefile parsing (#193)

Adding test cases for Corefile parsing.
Some code refactoring to allow test reuse.

middleware/kubernetes/k8stest/k8stest.go

@@ -0,0 +1,11 @@
+package k8stest
+
+import (
+	"net/http"
+)
+
+// checkKubernetesRunning performs a basic
+func CheckKubernetesRunning() bool {
+	_, err := http.Get("http://localhost:8080/api/v1")
+	return err == nil
+}