Cofactor files for caffeine example.

The tutorials section now provides files to be able to run an example for a Molecular Dynamics simulation of the Adenosine A2A receptor with Caffeine as cofactor. The topology (itp) and parameter (ff) files provided in gromacs format should be a good example to mimic for those interested in generating their own OPLS-AA parameters to use at GPCR-ModSim.

March 2, 2016