Add a wpa_supplicant rc script and bring in code to handle "WPA" in an

Add a wpa_supplicant rc script and bring in code to handle "WPA" in an
ifconfig_blah0="..." line in rc.conf. It should now be possible to bring
up a wireless interface with a line similar to:

ifconfig_iwi0="up WPA DHCP"

This commit also removes the restriction that when "DHCP" was specified,
the rest of the arguments were ignored. So the following should work now:

ifconfig_rl0="DHCP media 10baseT/UTP"

The commit also adds rc settings for interface renaming, e.g.:

ifconfig_iwi0_name="net0"
ifconfig_net0="up WPA DHCP"

Obtained-from: FreeBSD