adding options

- ability to update indicator

option.go

@@ -0,0 +1,10 @@
+package bolt
+
+type Option func(b *bolt)
+
+// sets the substring that must be present at the beginning of the message to indicate a command
+func WithIndicator(i string) Option {
+	return func(b *bolt) {
+		b.indicator = i
+	}
+}