Scope file handle to lifetime of BundleResource and BundleResourceStream

[jeffdiclemente]

This is a follow up enhancement which came from discussions in issue #299.

The idea is to keep the file handle open for the lifetime of the BundleResource and BundleResourceStream objects. The file handle will be closed once the last instance is destroyed.
Both these classes provide access to bundle resources and if no instances exist, there is no reason to maintain an open file handle.