Move to Paver for building

A fairly big reorganization of config and index files, in favor of using paver as the build system.  This build system is much more configurable, and I think clearer going forward.
Bug fix to hidecode option in activecode
Make auto builder compatible with new build process.  Also do some error checking on names and make sure no duplicate book names can be created.
Update dependencies and build process in the read me.
all books now compile without warning!  navhelp now navigates to the right course.
Remove index.rst from source
Change Makefile to use paver for transition period
Enable captchas on registration to keep out the spammers