Updates to FitRates_Mono.py default variables make it fail to reproduce expected example output

[DLafayetteII]

Development #7 made changes to not only the formating but the saved variables in the IRF. These variables need to be changed back to get something close to what is the expected output, namely:

'irf_type': 'GaussDiff' should be 'Gauss', and 'fwhm' :55 * ps should be 40 *ps.

Additionally, the pulse_power = 45 * nW needs to be 1000 * nW (This change was made in the 'small tweaks' patch)