gtburst Gui testing

From Don:
I download some data and then do the "Likelihood Analysis" as described in this thread:
https://fermi.gsfc.nasa.gov/ssc/data/analysis/scitools/gtburst.html
I don't bother with "Make spectra for XSPEC" or "Make navigation plots".  I don't think anyone uses those function these days.

This testing needs to be made into a Jupyter Notebook and ran during rc/main testing.