title: Receiving Passbook's .pkpass from URL without Webview
body: <p>Hi first of all i have to confess i really don't understand how the whole Passbook topic really works.
  So here's my situation: 
  I have a backend system which creates .pkpass files stores them and creates an URL.
  When i open this URL in my browser it directly starts to download the pass file.
  How can i receive or open this file with my ios application?</p>
  
  <p>Thanks in advance.</p>