Added reattach_activator

The other call is window.Intercom('reattach_activator');. If you remove the element that represents your inbox link from your page and then re-add it, the link between the inbox link and the message box is severed. You’ll need to call window.Intercom('reattach_activator');to set up this binding again.
Merge pull request #12 from niemyjski/patch-1

Added reattach_activator