Add initial cut of the issue priority feature

To validate the feature works, move existing issues with a
'deferred' status to priority 5.
Merge branch 'master' into refactor_lists_cpp
Assign priority to first few issues

Assign the priority recorded during the LWG Issaquah session for
the first 5 active issues in the issues list.  This is the final
proof-of-concept before applying a status to all active issues,
as recorded during that same Monday session at Issaquah.