bug(jinja): arch os has no osmajorrelase grain

[noelmcloughlin]

docker formula fails to render on archlinux.

    Rendering SLS 'base:docker' failed: Jinja variable 'dict object' has no attribute 'osmajorrelease'
/var/cache/salt/minion/files/base/docker/osfamilymap.yaml(44):

grains

...
    num_gpus:
        1
    os:
        Arch
    os_family:
        Arch
    osarch:
        x86_64
    oscodename:
        Arch Linux
    osfullname:
        Arch Linux
    osrelease:
    path: /usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl
...