Do not include shut wells in the well name to index map
The name to index map is used to make sure the correct wellstate values
are associated with the corresponding well. Shut wells should be
excluded from this mapping as no date is for shut wells are found in the
wellstates, instead 0 is outputed for the shut wells.
Merge pull request #678 from totto82/fix_eclipseWriter

Do not include shut wells in the well name to index map