fixes #2684 - add foreman-rake script to /usr/sbin

RPM builds:

http://ci.theforeman.org/job/packaging_build_matrix_rpm/93/
el6: http://koji.katello.org/koji/taskinfo?taskID=43814
fc18: http://koji.katello.org/koji/taskinfo?taskID=43811
fc19: http://koji.katello.org/koji/taskinfo?taskID=43813