ColorSensor::getAmbient() improved

• Changes getAmbient() back to using actions instead of raw values. This appears to improve the readings it provides (values in the range of 0.05-0.5 were experienced during testing).
• Also fixed a bug whereby a secondary constructor for Robot was not initialising speakers and buttons.

Downloads include;

• ShefRobot.zip, contains a compiled version of the library including dependencies and a usage README.
• ShefRobot.jar, contains a standalone compiled version of the library
• ShefRobot-docs.zip, contains a copy of the documentation for use offline.

Releases were built using JDK 1.8.0_60