Added placeholder image as part of second fix for bug issue #5.
Added single-use image alert feature as part of second fix for bug issue #5.  Now each WVFacebookFriend object requests its own image, so single-use tracking has been moved to the alerts manager.
With the second fix for bug issue #5, each WVFacebookFriend requests its own image.  It holds a UIImageView just long enough to cache the requested image in AFNetworking’s image cache.  Other objects can request a picture and receive either the cached image or a placeholder.
The second fix for bug issue #5 moved friend image fetching responsibility to the WVFacebookFriend object.  The error alert flag and queue, and the setTableCellImageViewForFriendRequest: function were no longer needed and were removed.  The new pictureCachedForRow: function asks the associated view to reload row data when a WVFacebookFriend object successfully fetches an image that was not already in the AFNetworking image cache.
Initial commit as part of second fix to bug issue #5.
Files automatically updated with changes corresponding to second fix for bug issue #5.