copyright: Add code for finding all copyright blocks and create a COPYING file

The end of the COPYING file was generated with:
% python ./util/find_copyrights.py configs src system tests util

Update -C command line option to spit out COPYING file

[ Some notes on this change.  1) I could add the find_copyrights.py function to the build to automatically generate the list.  Should we do that?  For now, I've appended the list to the COPYING file.  We should also probably get rid of the AUTHORS file.  What do you all think? (either that or we should update it) ]