scripts/configure.pl: add function to generate a nightly version string

scripts/configure.pl

@@ -2,6 +2,12 @@
 
 use warnings;
 use strict;
+use POSIX qw(strftime);
+
+
+sub nightly {
+    strftime "%Y%m%d", localtime;
+}
 
 
 our $CONFIG = do $ENV{GLUONDIR} . '/site/site.conf';