python version check when importing i2c and spi modules
read twice the first time and immediately after changing channels, once otherwise. removed the samples constructor parameter
Can get raw 8-bit signed or unsigned input channel values
can get raw value of input pins
Merge pull request #35 from npryce/python-version-check

python version check when importing i2c and spi modules
fixed switching channels
Merge pull request #36 from npryce/pcf8591-fixes

PCF8591 API fixes
added pcf8591 test harness schematic