Migration sql changes (#199)

* safe migration script changes

* lamassu migration script fixes

migrations/029-add_valid_to_user_config.js

@@ -2,7 +2,7 @@ var db = require('./db')
 
 exports.up = function (next) {
   var sql = [
-    'alter table user_config add column valid boolean not null'
+    db.addColumn('user_config', 'valid', 'boolean not null')
   ]
   db.multi(sql, next)
 }