gps todo - bug 376

handle the various GPS modes 

handle wake and sleep times 

handle maxint parameters

handle loss of lock at end of wake (gotLocThisTime)

if not sharing location, don't even power up the GPS

if we go to sleep without getting a location set hasValidLocation to false

properly handle time only modes

force gps sleep when in LightSleep and force wake only once <- confirm

fix has_gps based on new logic

add set router mode in python tool - it will also set GPS to stationary
(which will shrink DARK and NB period to zero and
 make light_sleep very long)

gps states

Active - for gps_attempt_time seconds
Sleeping - for (gps_update_rate or sleep forever) seconds
ForcedSleep - PowerFSM says we don't want to use GPS right now
(no need for sleep forever state)

gps triggers
GPS_TRIG_FORCE_SLEEP - from powerfsm
GPS_TRIG_FORCE_WAKE - from powerfsm
GPS_SETTINGS - if GPS settings changed, reset params and possibly become active