0.24 release update - proposed final RC3

Hi, folks. RC3 is now available.

http://people.apache.org/~jross/qpid-0.24-rc3/

This RC is signed and ready for promotion to GA. Supposing we don't
find any new critical issues, I will start the release vote on Friday.

Thanks!
Justin

0.24 release page: https://cwiki.apache.org/confluence/display/qpid/0.24+Release