take a stab at cleaning up our download pages:

take a stab at cleaning up our download pages:
* remove the boilerplates on various pages about how "easy" it is to build from source when we include a "installing from source" include at the same page
* remove text that mentions prehistoric and unsupported postgresql versions and/or OS platforms (yeah that means you PostgreSQL 8.4 and OSX for PPC...)
* pittis PPA is dead - long life apt.postgresql.org
* move the yum/rpm stuff to 9.4
* corrects some information about the apt repository wrt the support of ubuntu LTS-only
* update the fedora included versions with supported and upcoming fedora versions