DHT-sensor-library

Update example to note cycle threshold parameter for Arduino Due.

Resolve #24 by adding convert F to C function.

Resolve issue #20 by moving delay after 2 second read check to make read return quickly.

Switch to use noInterrupts and interrupts function. make read() public. This resolves pull #15.

Remove serial.print from library and update example error handling. Resolves issue #11 and #13.