install_server: split out reprepro to module aptrepo
Split the reprepro role out of the install_server module
as Faidon said on T132757.
Merge apt_repository into init.pp.
Rename module to "aptrepo", role to aptrepo::wikimedia.
Remove all the duplicate definitions of files and files
that had been replaced by templates.
Still need to check what's going on with "distributions vs.
distributions.erb" and "incoming vs. incoming.erb".