Version Control With Subversion Source

(Still more to do, but this is a good start.)

* src/en/ch-server-configuration.xml:

- new Overview section which describes pros/cons of servers
- new Overview section which makes explicit server recommendations
- lose a couple of obsolete-ish sidebars
- factorize path-based-authz description into its own section,
and make other the two server sections point to it
- new best-practice sidebar recommending not to use
path-based-authz unless absolutely necessary.