Rename COPYING to LICENSE to match libpwq/

git-svn-id: svn://svn.code.sf.net/p/libkqueue/code/trunk@643 fb4e3144-bc1c-4b72-a658-5bcd248dd7f7
Small cleanup for 2.0 release: remove Makefile.OLD it's available in the stable branch

git-svn-id: svn://svn.code.sf.net/p/libkqueue/code/trunk@644 fb4e3144-bc1c-4b72-a658-5bcd248dd7f7