#27 allow disabling Site path translation

[Stephen Savitzky]

The path translation done by the classes in the site
package interferes with Apache's path translation.
Among other things, this means that you can't just use

AddHandler cpia .xh

to pass .xh files off to cpia while allowing Apache to
handle the rest normally. It also seems to interfere
with the translation of "/" (the root) to "/index.html".

The advanced mapping in the site package is probably
useful in some cases, and it's essential in a stand-
alone server like the original PIA, but it isn't really
needed in Apache, and limits the ability of mod_cpia to
coexist with other parts of a complex website.

I'd recommend the use of a configuration directive to
selectively enable the site package.