Add configure script and Makefile template

This allows us to compile the Brewslave without the Arduino IDE and switch
certain features on and off at build time.
Fix compile time errors

Apparently, Ubuntu 12.04's avr-gcc is a bit more picky than the one provided
with the Arduino IDE.
Conditionally compile the Nokia LCD
Add support for the cheapo NTC temperature sensor
Return current instead of set temperature
Merge pull request #1 from matze/duemilanove-compat

Duemilanove compatibility