Add Sensor#touched? and Sensor#distance
Add touch and ultrasonic sensor examples
short sensor section in README
update sensor configuration API
Update README.md
Merge pull request #3 from Floppy/sensor-methods

Sensor instructions
Merge pull request #4 from Floppy/new-sensor-api

Simplified sensor configuration API
Merge pull request #1 from tehviking/master

Upstream changes