Save migrations file on db (#215)

* Revert "Migration sql changes (#199)"

This reverts commit 12c834469c.

* Save migrate file on db

* Add message on migration error in lamassu-update

migrations/017-user_tokens.js

@@ -3,12 +3,12 @@ var db = require('./db')
 exports.up = function (next) {
   var sql = [
     'drop table if exists users',
-    `create table if not exists user_tokens (
+    `create table user_tokens (
       token text PRIMARY KEY,
       name text NOT NULL,
       created timestamptz NOT NULL default now()
     )`,
-    `create table if not exists one_time_passes (
+    `create table one_time_passes (
       token text PRIMARY KEY,
       name text NOT NULL,
       created timestamptz NOT NULL default now()