apache.conf.in: overhaul gobbledygook

apache.conf.in: overhaul gobbledygook

A leaner, meaner, hopefully easier to understand example configuration
that's fully operational without requiring mod_rewrite for gitweb/fetch
access (mod_ssl, mod_authn_anon and mod_rewrite are always required for
https push access).

All User-Agent testing has been completely purged from the configuration.

Several things that were previously accomplished using mod_rewrite
have been replaced with non-mod_rewrite equivalents.

There are still benefits to enabling mod_rewrite for gitweb/fetch, but
it's no longer as important as it used to be.

Hopefully the new organization of the file makes it easier to under-
stand what's going on so that translating it to a non-Apache server
configuration file will be somewhat easier.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>