Major update - added sensors support, also fixed few bugs.

This is a major update. Key items:

1. Added sensors support infrastructure
2. Added BMP180 sensor support, for both Temperature and Pressure
readings.
3. Enabled watering logs Graphs (previously only table logs worked)
3.1 Put together new GraphZone function and supporting infrastructure
that uses CSV logs
3.2 Changed flot javascript files to short names since SdFat on Arduino
does not support long file names
4. Fixed incorrect file size in the logs directory listing (previously
it was truncated to 16bit by mistake)
5. Renamed sd-log files to sdlog, since Arduino IDE does not like to
have special characters in the file name