Ticket #48227 rpm.mk doesn't build srpms for 389-ds and nunc-stans
https://fedorahosted.org/389/ticket/48227
Reviewed by: nhosoi (Thanks!)
Branch: master
Fix Description: Add makefile macros for the nunc stans tarball name
and url. Grab the nunc stans tarball from the url with wget and
copy it to the SOURCES.
Platforms tested: Fedora 21
Flag Day: no
Doc impact: no