Fixed issue with poll on sysfs /sys/class/gpio value on boot, closes #96 
Fixed issue with poll on sysfs /sys/class/gpio value on boot, closes #96 

Opening the fp as RW fixes the issue of poll blocking forever the first time a program is launched after boot.
Alternatively, do a dummy poll with POLLIN|POLLOUT (for example just before the dummy read).
uraimo/SwiftyGPIO,uraimo/SwiftyGPIO