A framework for crawling pages in the congressional record.

By default, this crawls pages starting from the Daily Issues page
(http://thomas.loc.gov/home/Browse.php?&n=Issues), visiting each issue in
a depth-first fashion.

## Synopsis

   use WebService::LOC::CongRec::Crawler;
   use Log::Log4perl;
   Log::Log4perl->init_once('log4perl.conf');

   $crawler = WebService::LOC::CongRec::Crawler->new();
   $crawler->goForth(process => \&process_page);

   sub process_page {
       my ($day, $page) = @_;
       my $logger = Log::Log4perl->get_logger('thomas.pl.process_page');

       $logger->info("Page #$i ID " . $page->pageID);
       exit if ++$i > $max;
   }