[Sensor] The event.reading.illuminance is too low in AmbientLight.js

[xiaolongx]

Flashing AmbientLight.js with commit 31c3908 on Arduino 101, the event.reading.illuminance is too low even using flashlight.

Ambient light test...
zjs_sensor_create: unsupported frequency, defaulting to 50Hz
state: activating
ipm_console0: 'start ambient light 12'
state: activated
(very dark): 0.00019422420860140712
(very dark): 0.0001910913093819011
(very dark): 0.00019422420860140712

[jimmy-huang]

@xiaolongx, @qiaojingx is this still reproducible?

[qiaojingx]

Verified with commit 9777997 on Arduino 101.
This issue will not be reproduced if wire sensor's power to Arduino 5V.

But if wire sensor's power to Arduino 3.3V. The event.reading.illuminance is still too low.

[jimmy-huang]

Ok, this make sense, I'll probably update the wiring instructions in the same to attach to sensor only to 5v instead.