Add command line option for path to configuration file

Allow user to pass the path to the configuration file into the
site-generator.

site-generator

@@ -9,6 +9,7 @@
 	site-generator [OPTION]... PAGE|PAGE=<comma separated list of ids>...
 
 	-a, --all       generate all pages defined in configuration file
+	-c, --configure path to configuration file
 	-l, --list      print list of configured pages
 	-p, --preview   print generated pages to standard out
 	-q, --quiet     suppress progress information while generating pages
@@ -109,11 +110,13 @@ sub main {
 
 	# Argument parsing
 	my $all;
+	my $configuration_path;
 	my $preview;
 	my $verbose;
 	my $quiet;
 	GetOptions(
 		'all'			=> \$all,
+		'configuration=s' => \$configuration_path,
 		'list'			=> \&print_available_pages,
 		'preview'		=> \$preview,
 		'verbose'		=> \$verbose,
@@ -126,8 +129,19 @@ sub main {
 		$verbose = 'quiet';
 	};
 
+	if (!$configuration_path) {
+		$configuration_path = "site.cfg";
+	}
+
+	my %config;
+	if ( -f $configuration_path ) {
 		# Load config file
-	read_config "site.cfg" => my %config;
+		read_config $configuration_path => %config;
+	}
+	else {
+		print STDOUT "Could not read configuration file: $configuration_path\n"; 
+		exit 1;
+	}
 
 	my $tt = get_template_html($config{DBI});