ceph-detect-init: FreeBSD introduction of bsdrc

ceph-detect-init: FreeBSD introduction of bsdrc

ceph-detect-init/ceph_detect_init/freebsd/__init__.py
    New file

ceph_detect_init/__init__.py: Only test FreeBSD after it is not Linux

    If we do it the other way around it will not work during testing on FreeBSD
    because it will always have platform.system() == FreeBSD
    So first test for Linux, and only then check to see if it is FreeBSD.

ceph-detect-init/tests/test_all.py: add tests for FreeBSD
ceph-detect-init/run-tox.sh: ReEnable to run test for FreeBSD

Signed-off-by: Willem Jan Withagen <wjw@digiware.nl>
Signed-off-by: Kefu Chai <kchai@redhat.com>