Updated the wiki info on the RPMs

Hi all

I found some very obsolete info on RPM building on the wiki, so I've cut
most of it and replaced it with a minimal explanation:

https://wiki.postgresql.org/wiki/RPM_Packaging

I've also removed https://wiki.postgresql.org/wiki/RPM_Installation as
it was obsolete and misleading.


I can't fix this, but would like to delete
http://svn.pgrpms.org/wiki/FedoraPackageList in favour of saying that
you should just:

  yum groupinstall "Development Tools"
  yum install rpmbuild yum-utils rpmdevtools rpm-sign
  yum-builddep postgresql-9.4.spec


-- 
 Craig Ringer                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services