GeneralOptions copy 'n' paste bug

This looks like a simple copy 'n' paste bug.  The code in
GeneralOptions.GetParameters is checking against limit.HasValue for
limit, offset, and sort.  Updated to check offset.HasValue for offset,
and sort.HasValue for sort.
Merge pull request #8 from WaywardMage/master

Fixed the bug in GeneralOptions where is wasn't setting the offset and sort parameters