Add support for Turbolinks 2.X

Intercom is not configured to work with Turbolinks. This commit forces Intercom to reload it's messenger when a new page loads via the following line of code:

    document.addEventListener('page:load', l, false)

This was inspired by the following PR:

intercom#215

I am testing this branch via Intercom's instructions:

https://github.com/intercom/intercom-rails#running-testsspecs

lib/intercom-rails/script_tag.rb

@@ -98,8 +98,8 @@ def find_lead_attributes
     def intercom_javascript
       intercom_settings_json = ActiveSupport::JSON.encode(intercom_settings).gsub('<', '\u003C')
 
-      str = "window.intercomSettings = #{intercom_settings_json};(function(){var w=window;var ic=w.Intercom;if(typeof ic===\"function\"){ic('reattach_activator');ic('update',intercomSettings);}else{var d=document;var i=function(){i.c(arguments)};i.q=[];i.c=function(args){i.q.push(args)};w.Intercom=i;function l(){var s=d.createElement('script');s.type='text/javascript';s.async=true;s.src='#{Config.library_url || "https://widget.intercom.io/widget/#{j app_id}"}';var x=d.getElementsByTagName('script')[0];x.parentNode.insertBefore(s,x);}if(w.attachEvent){w.attachEvent('onload',l);}else{w.addEventListener('load',l,false);}};})()"
-
+      str = "window.intercomSettings = #{intercom_settings_json};(function(){var w=window;var ic=w.Intercom;if(typeof ic===\"function\"){ic('reattach_activator');ic('update',intercomSettings);}else{var d=document;var i=function(){i.c(arguments)};i.q=[];i.c=function(args){i.q.push(args)};w.Intercom=i;function l(){var s=d.createElement('script');s.type='text/javascript';s.async=true;s.src='#{Config.library_url || "https://widget.intercom.io/widget/#{j app_id}"}';var x=d.getElementsByTagName('script')[0];x.parentNode.insertBefore(s,x);}if(w.attachEvent){w.attachEvent('onload',l);}else{w.addEventListener('load',l,false);document.addEventListener('page:load', l, false);}};})()"
+      
       str
     end