Added a constant FEEDWORDPRESS_USER to restrict who feed authors are set to.

I added a constant, when defined FEEDWORDPRESS_USER that will set the author to whatever the username is.  It will also list the authors based on the syndicated_source_author name in the post meta.  The net result is that the person can click on the author's name and see a listing of posts by that author even though the "real" author is FEEDWORDPRESS_USER
There is also a change to the performance section where you can replace and make more efficient IN queries.