button-hotplug: Add KEY_WLAN handling

This extends button-hotplug to map KEY_WLAN to rfkill hotplug
events, enabling /etc/rc.button/rfkill script to work properly on
routers with KEY_WLAN buttons.
Add userspace support for Sagemcom F@ST2704V2 ADSL router

This adds userspace support for Sagemcom F@st 2704 router.
Add profile and build image for Sagemcom F@ST2704V2 ADSL router

This adds profile and build image for Sagemcom F@st2704, using b43
driver.
For WiFi to work properly BCMA fallback SPROM support patch must
be applied (http://git.io/z1Ki8A).