Remove extraenous setup file

Through some merging mistake 15_setup_repos and 15_install_repositories became
duplicated. Deleted 15_install_repositories because the name is longer and it
has slightly older code in it I believe.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #737 from kbarber/maint/1.5.x/remove_duplicate_setup_file

Remove extraenous setup file