Use dhandle hash lists in more places.  Adjust sweep timings. #1460

@agorrod Please review this set of changes.  I implemented a few of the dhandle list walk optimizations that I mentioned in #1460.  I also took a compromise position on the sweep timings, setting them to 30 seconds TOD and 10 second sweep period.
I don't understand the ```!file:``` part of this condition. What are we trying to put into the metafile bucket here? I ask because some work on my todo list is to move LSM and table handles to be dhandles, and then they will become part of these lists.