Added the 'NS R1rho 2-site' R1rho calculating function to the relax library.

This is the numerical model for the 2-site Bloch-McConnell equations for R1rho data.

This code originates from the Skrynikov & Tollinger code (the sim_all.tar file
https://gna.org/support/download.php?file_id=18404 attached to https://gna.org/task/?7712#comment5).
Specifically the funNumrho.m file.

This commit follows step 3 of the relaxation dispersion model addition tutorial
(http://thread.gmane.org/gmane.science.nmr.relax.devel/3907).
Fix for the function name in the lib.dispersion.ns_r1rho_2site module and removed misplaced copyrights.