Changed scanEIT.py to scan axial B-field.

Also added plot of polarization rotation to output plot.

Changed output plot format to 'png' for compatibility with existing documents.
Changed couplings and decays:
Moved light polarization to parallel to transverse B-field.
Changed decay factors from excited to ground states so it would be isotropic and add to 1.

Also changed order in SystemParameters struct so it matches argument order.
Attemp to add source terms to KSP solve.
Also fixed Gfactor errors in Zeeman couplings from ADM Package.
Merge pull request #1 from dihm/upstream-hotfixes

Fixes for EIT example from David.