Database migration initialization

This commit introduces a day 0 set of building blocks to implement a
database migration framework into the sqlite database. Adding the
following changes:

- Introduce the `golang-migrate` project as a dependency and vendor it
- Introduce a `db_migrations` folder with an initial no-op migration to
bootstrap the initial database version for newly created databases
- Update the initialization of the database when creating the initial
schema to hard set the database migration version on db creation
before loading any data

This commit does not introduce a method of actually running future
migrations against existing databases -- that is left for future
implementation based on this groundwork when a set of commands that
updates the database in place exists and requires the migration.

The intention of this commit is also to ensure that future initialized
registry databases have an initial version that can be used for
migrations in future releases.

Author: kevinrizza

cmd/configmap-server/main.go

@@ -98,7 +98,7 @@ func runCmdFunc(cmd *cobra.Command, args []string) error {
 		logger.Fatalf("error getting configmap: %s", err)
 	}
 
-	sqlLoader, err := sqlite.NewSQLLiteLoader(dbName)
+	sqlLoader, err := sqlite.NewSQLLiteLoader(dbName, "")
 	if err != nil {
 		return err
 	}

cmd/initializer/main.go

@@ -53,7 +53,7 @@ func runCmdFunc(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
-	dbLoader, err := sqlite.NewSQLLiteLoader(outFilename)
+	dbLoader, err := sqlite.NewSQLLiteLoader(outFilename, "")
 	if err != nil {
 		return err
 	}