update example.php with namespace changes: HipChat\HipChat_Exception

The new version catches exceptions correctly.
The old version could result in "Fatal error: Uncaught exception 'HipChat\HipChat_Exception'".
You can verify this by using a Notification token (which has insufficient privileges), instead of an Admin token.

example.php

@@ -24,7 +24,7 @@
     $room_data = $hc->get_room($room->room_id);
     echo " - Participants: ".count($room_data->participants)."\n";
   }
-} catch (HipChat_Exception $e) {
+} catch (HipChat\HipChat_Exception $e) {
   echo "Oops! Error: ".$e->getMessage();
 }
 
@@ -39,6 +39,6 @@
     $user_data = $hc->get_user($user->user_id);
     echo " - Status: ".$user_data->status."\n";
   }
-} catch (HipChat_Exception $e) {
+} catch (HipChat\HipChat_Exception $e) {
   echo "Oops! Error: ".$e->getMessage();
 }