Add is_bsd() to neutron-lib
Add is_bsd() to neutron-lib

The is_bsd() testtool function is required for skipping
some of the test cases in OSX/BSD environment.

The is_bsd() check is useful when projects want to skip
test cases related to IPv6 formatting as the implementation
of netaddr differs in different platforms.

Change-Id: I664e55883bbd714e31b49b278060e625fc5e6ea4
Related-Bug: #1484837

openstack/neutron-lib,openstack/neutron-lib,openstack/neutron-lib,openstack/neutron-lib