fixed ls_alias for OpenBSD as it lacks the -G switch
fix ls_alias for NetBSD as well
pin requests to 2.4.1 on travis

bug in requests 2.4.2 doesn't allow unicode URLs on Python 2
added comment on reason for seperate ls_alias for OpenBSD/NetBSD
forbid known-bad requests-2.4.2
Merge pull request #6625 from bsvh/master

Fix ls_alias for certain BSDs
Merge pull request #6630 from minrk/travis-requests-2.4.1

forbid broken requests-2.4.2 on travis