add numeric attributes expire and retry

[stephenedwards]

Priority 2 messages requires attributes "retry" and "expire". added attributes accordingly.

[erniebrodeur]

It's in the dev branch, thank you! I'll cut a new version in the next few days.

[stephenedwards]

Hi,

Any idea on when a new version will be available?

[erniebrodeur]

Hey Stephen, that change didn't quite pass muster once I looked at it and how it broke specs. Then I got sidetracked on various other bits. I'll take another look at it htis weekend.