Add OpenILS::WWW::Proxy::Authen Module

Add OpenILS::WWW::Proxy::Authen Module

Enables HTTP Basic Authentication access control.

Uses the OILSProxyPermissions and OILSProxyLoginType settings, but prompts
are controlled by the Apache AuthName directive.

This module allows things like Directory Indexing and non-perl or otherwise
incompatible with the normal proxy module Response (or similar) handlers to
be password-protected.

It also supports the OpenILS::WWW::Proxy user/passwd CGI params to allow
an easier transition between the two.

For example:

<Location /authen_login/>
    Options +Indexes
    PerlOptions +GlobalRequest
    PerlSetVar OILSProxyPermissions "VIEW_REPORT_OUTPUT"
    PerlSendHeader On
    AuthType Basic
    AuthName "Notices Login"
    PerlAuthenHandler OpenILS::WWW::Proxy::Authen
    require valid-user
    allow from all
</Location>

Signed-off-by: Thomas Berezansky <tsbere@mvlc.org>