add Schema::Versioned support

Netdisco/bin/upgrade_netdisco_schema_version.pl

@@ -0,0 +1,18 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings FATAL => 'all';
+
+use Dancer ':script';
+use Dancer::Plugin::DBIC 'schema';
+
+use Netdisco::DB;
+use Try::Tiny;
+
+if (not schema->get_db_version()) {
+  # installs the dbix_class_schema_versions table with version "0"
+  schema->install("0");
+}
+
+# upgrades from whatever dbix_class_schema_versions says, to $VERSION
+schema->upgrade();