Hamilton definition in run_two_bands.py differs from equation

The order of operators for the hamiltonian in run_two_bands.py are not identical with the Hamiltonian Eq. in Notebook 10.

See

```python
h_int += -J*c_dag('up-%s'%o1,0)*c_dag('down-%s'%o1,0)*c('up-%s'%o2,0)*c('down-%s'%o2,0)
h_int += -J*c_dag('up-%s'%o1,0)*c_dag('down-%s'%o2,0)*c('up-%s'%o2,0)*c('down-%s'%o1,0)
```