Optimize bplib_load retrieval of active bundles

[jpswinski]

In bplib_load the code retrieves the oldest active bundle from the storage service on every call to check if it has timed-out or expired. This retrieval from the storage service is unnecessary, and there are a few options to optimize it:

• check the timeout using the active table retx time and only do a retrieval if it has timed out (this suffers from potentially leaving expired but not-timed-out bundles in the active table, since the expiration time is not stored in the active table)
• move the expiration time into the active table and check both the timeout and the expiration time without doing a bundle retrieval.

[jpswinski]

The first recommended option from the initial description was taken.