i2c.scan() implemented as multi-byte writes

[charkster]

I was not able to detect the VCNL4010 ambient light sensor, as it will not ACK to a write to an invalid internal address (0x00 is not valid). This has the effect of the sensor not being detected from the i2c.scan() function. A further look at the i2c.scan() function sees it implement as multi-byte writes, which is not the spec recommended I2C quick commands.

[charkster]

Pull request #11 created which successfully detected all my i2c sensors.