Migration sql changes (#199)

* safe migration script changes

* lamassu migration script fixes

migrations/1514981004673-add_serial_to_logs.js

@@ -1,7 +1,9 @@
 const db = require('./db')
 
 exports.up = function (next) {
-  const sql = ['alter table logs add column serial integer not null default 0']
+  const sql = [
+    db.addColumn('logs', 'serial', 'integer not null default 0')
+  ]
   db.multi(sql, next)
 }