Add some FreeBSD facts

added:
 * ansible_distribution
 * ansible_distribution_release 
 * ansible_distribution_version
 * ansible_os_family
 * ansible_pkg_mgr
 * ansible_ssh_host_key_ecdsa_public

Also adds ECDSA public key for all plaforms.
Merge pull request #3055 from kubicek/freebsd

Add some FreeBSD facts