split out 2.4 support into Apache24::AuthCookie

Added:
- Apache2::AuthCookie::Base
    - common methods for Apache2::AuthCookie, Apache24::AuthCookie
    - Apache2::AuthCookie and Apache24::AuthCookie inherit from this
- Apache24::AuthCookie
    - the main module to inherit from for httpd 2.4 support.
    - Auth API has changed in apache 2.4, so a new module is needed to
      support this version.  Apache2::AuthCookie will remain for
      versions 2.2 and earlier.
test cgi scripts: do not try to load mod_perl.pm
Merge branch 'master' into httpd24