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

lib/db-migrate-store.js

@@ -0,0 +1,22 @@
+const db = require('../lib/db')
+
+const upsert = 'insert into migrations (id, data) values (1, $1) on conflict (id) do update set data = $1'
+
+function DbMigrateStore () {
+}
+
+DbMigrateStore.prototype.save = function (set, fn) {
+  let insertData = JSON.stringify({
+    lastRun: set.lastRun,
+    migrations: set.migrations
+  })
+  db.none(upsert, [insertData]).then(fn).catch(err => console.log(err))
+}
+
+DbMigrateStore.prototype.load = function (fn) {
+  db.one('select data from migrations').then(({ data }) => {
+    fn(null, data)
+  })
+}
+
+module.exports = DbMigrateStore