Runtime (#1160)

* Add String to Runtime interface

* Setup Dynamic Runtime Configuration

runtime/kubernetes/kubernetes.go

@@ -2,7 +2,9 @@
 package kubernetes
 
 import (
+	"errors"
 	"fmt"
+	"strings"
 	"sync"
 	"time"
 
@@ -245,6 +247,10 @@ func (k *kubernetes) Init(opts ...runtime.Option) error {
 		o(&k.options)
 	}
 
+	if strings.HasPrefix(k.options.Source, "github.com") {
+		return errors.New("invalid source provided to kubernetes runtime, expected docker image")
+	}
+
 	return nil
 }