Modified the 'mode' in setter.
Modified the 'mode' in setter.

It seems to be working . However, there are some modes which may not
work properly. I'm not sure yet, I have to test the setter to find out.


Former-commit-id: 73016dcdfe7e47091942a888d4345918ae124310
Former-commit-id: e54959cffa6546a2855bc592286efa2d12f8fc1b
amdouglas/OpenPNM,PMEAL/OpenPNM,TomTranter/OpenPNM,stadelmanma/OpenPNM,amdouglas/OpenPNM