SciPy FFT import needs to be updated

[luke-skywalker]

For this to work on current NumPy, line 53 of beepdetect.py must be changed from
from scipy import fft
to
from scipy.fft import fft.
Other than that, it runs without issues.

ps. I also did a number of other changes to the other files, in order to:

• use systemd;
• have a pushbutton to shutdown the pi without having to log in to the web interface.
• have a status LED indicating whether the pi is operational or down.

If I find time I'll put all of this together, clone, and make a pull request.
Thanks for the great work!