Add example script for database tables, starting with db_version table

for tracking the database version.

src/sql/00-metrics-tables.sql

@@ -0,0 +1,15 @@
+/*
+ * Script for loading the core metrics tables in an empty database.
+ */
+
+/*
+ * db_version -- table to store the version history of this database
+ */
+CREATE SEQUENCE db_version_id_seq;
+CREATE TABLE db_version (
+  db_version_id   INT8 default nextval ('db_version_id_seq'), -- the identifier for the version
+  version         VARCHAR(250),     -- the version number
+  status          INT8,             -- status of the version, 1 if its the current version
+  CONSTRAINT db_version_pk PRIMARY KEY (db_version_id)
+);
+INSERT into db_version (version, status) VALUES ('0.0.1', 1);