add migration for crypto support

migrations/005-addCrypto.js

@@ -0,0 +1,18 @@
+var db = require('./db')
+
+exports.up = function (next) {
+  var sqls = [
+    'alter table transactions alter satoshis TYPE bigint',
+    "alter table transactions add crypto_code text default 'BTC'",
+    "alter table pending_transactions add crypto_code text default 'BTC'",
+    'alter table pending_transactions alter satoshis TYPE bigint',
+    "alter table bills add crypto_code text default 'BTC'",
+    'alter table bills alter satoshis TYPE bigint'
+  ]
+
+  db.multi(sqls, next)
+}
+
+exports.down = function (next) {
+  next()
+}