Fix for Epson V550

With the Epson V550, the maximum scanner resolution is a function of the
area to be scanned. To make the higher resolutions available, in
datasource.cs, you need to set the area to be scanned first, then set
the resolution.
Revert "Fix for Epson V550"

This reverts commit 9e023e8ac06008d961731f7f1a5883562e1d397e.
Fix for Epson V550

On the Epson V550 scanner, the maximum resolution is a function of the
area to be scanned. To make the higher resolutions available, in
datasource.cs, the area to be scanned needs to be set before the
resolution is set.
Merge pull request #17 from ijourneaux/master

Change to datasource.cs to handle Epson V550