Make the DHT22 work with a clock frequency of 8MHz by playing with the undocumented _counter variable in the constructor.

Before, the sensor would return 0 for temperature and humidity because the timing (based on the clock speed) was off.
Use _counter to adapt for different clock speeds. I didn't have any luck when running with 1Mhz - maybe a oscilloscope would help here.

I modified the boards.txt to run the Sensor328p with 8MHz:
s328o1.name=Sensor328p (int1MHz, 1.8V, devduino v2)
s328o1.upload.protocol=arduino
s328o1.upload.maximum_size=30720
s328o1.upload.speed=19200
s328o1.bootloader.low_fuses=0x62
s328o1.bootloader.high_fuses=0xda
s328o1.bootloader.extended_fuses=0x06
s328o1.bootloader.path=atmega
s328o1.bootloader.file=ATmegaBOOT_168_atmega328_pro_8MHz.hex
s328o1.bootloader.unlock_bits=0x3F
s328o1.bootloader.lock_bits=0x0F
s328o1.build.mcu=atmega328p
s328o1.build.f_cpu=8000000L
s328o1.build.core=arduino
s328o1.build.variant=standard
Merge branch 'master' of github.com:shubrich/sensorNet