Add tail fitting in gf_imfreq

  modified:   pytriqs/base/gf/local/gf_imfreq.py
  modified:   pytriqs/solvers/ctqmc_hyb/ctqmc_solver.pyx
Add two furthers scripts for testing ctqmc_hyb

The scripts are there so that manual tests can be
made easily. They are not (yet) run in the make test.

  new file:   pytriqs/solvers/ctqmc_hyb/test/global_moves.py
  new file:   pytriqs/solvers/ctqmc_hyb/test/time_acc.py