Merge pull request #8 from Vido/master

New properties .state and .mode
Fixing bug on rpi.py: _get_pin_state returned 0, 1 and shoud return pingo.LOW or pingo.HIGH
adding MCP3008 support for analog input in Raspberry Pi (work in progress)
working on spi integration and analog input example dojo_display7.py
moving spi package to rpi, as it depends on RPi.GPIO
Merge pull request #9 from Vido/master

GhostBoard HTML Interface
fixing documentation
Changed pin method names: low() -> off(), high() -> on()
added print() calls to test ghost; added toggle() test
fixed var name grammar
added pin_states.json to .gitignore
Fixing the .json file issue
The .json files is no longer tracked.