Updates datasets load script and unit test to account for change in filename of remote data cubes, and additional Vela remote data files
Adds normalize kernel option to irf psf_table EnergyDependentTablePSF and unit test
Adds predicted counts cube tutorial, including plotting scripts and updates doc index.rst file to accomodate new addition
Updates tutorial index rst page for new npred tutorials and makes further modifications to predicted_counts.rst
Updates references.rst file in docs to include FSSC Fermi Tools reference