add udev rules and script for non-root access to gpio

Refer to Issue #137 for details:
  Access to GPIO and PWM as non-root user not functioning
  #137

udev/80-non-root-gpio-permissions.rules

@@ -0,0 +1 @@
+KERNEL=="gpio*", SUBSYSTEM=="gpio", ACTION=="add", PROGRAM="/usr/local/bin/udev-non-root-gpio-permissions.sh"

udev/udev-non-root-gpio-permissions.sh

@@ -0,0 +1,46 @@
+#!/bin/bash
+
+# Result: chown debian:debian /sys/class/gpio
+
+chown -R debian:debian /sys/devices/gpio
+chown -R debian:debian /sys/class/gpio
+chown -R debian:debian /sys/devices/platform/ocp
+chown -R debian:debian /sys/class/pwm
+
+#GPIO ( active_low device direction edge power subsystem uevent value )
+find /sys/class/gpio -type d -exec chmod 2770 {} \;
+find /sys/class/gpio -name "direction" -exec chmod 0660 {} \;
+find /sys/class/gpio -name "edge" -exec chmod 0660 {} \;
+find /sys/class/gpio -name "value" -exec chmod 0660 {} \;
+find /sys/class/gpio -name "active_low" -exec chmod 0660 {} \;
+find /sys/class/gpio -name "device" -exec chmod 0660 {} \;
+find /sys/class/gpio -name "power" -exec chmod 0660 {} \;
+find /sys/class/gpio -name "subsystem" -exec chmod 0660 {} \;
+
+#PWM ( duty_cycle enable period polarity power uevent )
+find /sys/devices/platform/ocp -name "duty_cycle" -exec chmod 0660 {} \;
+find /sys/devices/platform/ocp -name "enable" -exec chmod 0660 {} \;
+find /sys/devices/platform/ocp -name "period" -exec chmod 0660 {} \;
+find /sys/devices/platform/ocp -name "polarity" -exec chmod 0660 {} \;
+find /sys/devices/platform/ocp -name "power" -exec chmod 0660 {} \;
+find /sys/class/pwm -name "duty_cycle" -exec chmod 0660 {} \;
+find /sys/class/pwm -name "enable" -exec chmod 0660 {} \;
+find /sys/class/pwm -name "period" -exec chmod 0660 {} \;
+find /sys/class/pwm -name "polarity" -exec chmod 0660 {} \;
+find /sys/class/pwm -name "power" -exec chmod 0660 {} \;
+
+chmod 0220 /sys/class/gpio/export
+chmod 0220 /sys/class/gpio/unexport
+chmod 0220 /sys/class/pwm/export
+chmod 0220 /sys/class/pwm/unexport
+
+find /sys/class/gpio -name "uevent" -exec chmod 0660 {} \;
+find /sys/class/gpio -name "autosuspend_delay_ms" -exec chmod 0660 {} \;
+find /sys/class/gpio -name "control" -exec chmod 0660 {} \;
+find /sys/class/pwm -name "uevent" -exec chmod 0660 {} \;
+find /sys/devices/platform/ocp -name "uevent" -exec chmod 0660 {} \;
+
+# Additional code for getting AIN pins set up
+ain_activator=/sys/devices/platform/bone_capemgr/slots
+chown -R debian:debian $ain_activator/
+chmod -R 2770 $ain_activator/