fixed apachex_installed_version fact and apachex::package

  Summary of changes:

    - added 'www/apache22-xx-mpm' to search list in
      lib/facter/apachex_installed_version.rb
    - reorganized package deinstallation code in manifests/package.pp
      (FreeBSD), now it's only the currently installed apache package
      is deinstalled when a new version has to be installed