Iterated smoother casenames

Fix in iterated smoother casenames, the following is now true for iterated smoother: 

For iterated smoother:
Assume format string ITER_CASE_FMT = "case%d"

1.Select case0.
2. Simulate in runpath/iter0 and store simulated results in Storage/case0.
3. Update based on simulation results from Storage/case0, and store updated parameters in Storage/case1.
4. Simulate in runpath/iter1 and store simulated results in Storage/case1.
5. Update based on simulation results from Storage/case1, and store updated parameters in Storage/case2.