Implements Invalid Token Handler (#622)

* Drops unneeded logout check

* Restores Authenticated check on Logout

* Extracts resetAuthToken

* Renames SPAuthenticationDidFail > SPAuthenticationTokenInvalid

* New TokenInvalid Handler

* Revert "New TokenInvalid Handler"

This reverts commit 0cbc925.

* Revert "Renames SPAuthenticationDidFail > SPAuthenticationTokenInvalid"

This reverts commit 966f2fd.

* Revert "Extracts resetAuthToken"

This reverts commit 79204f3.

* Revert "Restores Authenticated check on Logout"

This reverts commit 82109fb.

Author: Jorge Leandro Perez

Simperium/Simperium.m

@@ -587,12 +587,7 @@ - (NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication *)sende
 #pragma mark ====================================================================================
 
 - (void)signOutAndRemoveLocalData:(BOOL)remove completion:(SimperiumSignoutCompletion)completion {
-    
-    // Don't proceed, if the user isn't logged in
-    if (!self.user.authenticated) {
-        return;
-    }
-    
+        
     if (self.logoutInProgress) {
         SPLogError(@"Error: Simperium is already logging out");
         return;