title: How to dispose of a ViewModel in Durandal after Logout
body: <p>I might be on the wrong track here, but here goes:</p>
  
  <p>In my PhoneGap Durandal app, I have a Profile View/VM which only returns data the first time it is hit - after that it checks a bool called initialised and wont hit the DB again the 2nd time. This works fine. </p>
  
  <p>However after Logout, I need to invalidate the cache. I could use a message to tell the Profile VM to clear the variable (ie. invalidate the cache) but I thought perhaps there is a higher-level way of doing this in Durandal - e.g. On Logout, I tell dispose of all ViewModels in memory (there may be other Singleton objects with session specific info in them). </p>
  
  <p>Advice please...</p>