Runtime (#1160)

* Add String to Runtime interface

* Setup Dynamic Runtime Configuration

runtime/local/local.go

@@ -0,0 +1,11 @@
+// Package local provides a local runtime
+package local
+
+import (
+	"github.com/micro/go-micro/v2/runtime"
+)
+
+// NewRuntime returns a new local runtime
+func NewRuntime(opts ...runtime.Option) runtime.Runtime {
+	return runtime.NewRuntime(opts...)
+}