at: use old privs model and other fixes
This update fixes the following issues with at:
- bnc#849720: use old privs model
- do not install sysvinit script and service file together
- add sticky bit to atjobs
- adding service hook was in %verifyscript section not in %post
- at must use secure_getenv.
- Submitted by Michal Vyskocil (mvyskocil)
Fixed bugs
bnc#849720
"at" command immediately exit with: Cannot create atjob file /var/spool/atjobs/...: Permission denied