title: Hiding a Facebook ID from the page's source
body: <p>I know the title might not be very explicit, but here's my problem:
  All of the users on my website are connected via Facebook. And since their facebook picture is displayed on their profile, anybody can view the page's source and find their Facebook ID (I am using <code>https://graph.facebook.com/*Facebook id*/picture</code> as a source for the picture). Should I be concerned about this? Is there any way to "hide" this information to the visitor?</p>