Added CSP-MZN-2013 folder.

This scenario contains a collection of 4642 CSP instances encoded in MiniZinc format, coming from the Third International CSP Solver Competition (http://cpai.ucc.ie/08/), the MiniZinc 1.6 benchmarks (http://www.minizinc.org/g12distrib.html), and the MiniZinc Challenge 2012. The suffix "-2013" refers to the year we ran the experiments. We used 11 different solvers that attended the MiniZinc Challenge 2012, namely: bprolog, fzn2smt, g12cpx, g12fd, g12lazyfd, g12mip, gecode, izplus, minisatid, mistral, and ortools.