Static IP support on bridge

Assign static ip to bridged interface

Usage for static ip:
config.vm.network :bridged, "192.168.1.10"
config.vm.network :bridged, "192.168.1.10", :bridge => "en0: Wi-Fi (AirPort)",:netmask => "255.255.255.0"

Usage for dhcp:
config.vm.network :bridged
config.vm.network :bridged, :dhcp, :bridge => "en0: Wi-Fi (AirPort)"

I needed it for my development network, it seems there is others too (Issue #743)