ugps: add a minimal gps daemon

* set the system time/data
* "ubus call gps info" will tell you lattitude, longitude, elevation, speed and bearing

Signed-off-by: John Crispin <blogic@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@41929 3c298f89-4303-0410-b956-a3cf2f4a3e73