Adding a Header field in "Faces" message?

Hi @bmcdorman, @eshort:

Was there any particular design reason for not including a ```std_msgs/Header``` field in the Faces message that the ```openface_ros``` node publishes?

In order to sync the audio data with the visual data in a single ROS node, I was thinking of using the time synchronizer from the [message_filters](http://wiki.ros.org/message_filters#Time_Synchronizer) package with an [approximate time](http://wiki.ros.org/message_filters#ApproximateTime_Policy) policy. But doing so requires that the messages from both topics have a header field.

Would it be appropriate to include this field in the Faces message?