Corrected pnCCD Main notebooks for path to slow data, etc.

Dear Karim, I modified the main notebooks of pnCCD. After talking to Robert Hartmann from PNSensor, we decided to take the temperatures of both pnCCD sensors into account instead of just taking the temperature of top sensor into account. So, I added the temperatures as:

top_temperature bottom_temperature

However, the above parameters need to be defined in a file where you had kindly defined all the pnCCD conditions (for injection into the calibration database). Could you please do me a favor and delete "temperature" from conditions and replace it by the two above parameters instead? Otherwise, when you run these notebooks, you will get an error complaining that the above parameters are not defined. Thank you very much. I appreciate it a lot.

Best Regards, Kiana