Add tests and fixes for rehydration

* Barracks must get an initial state or state.location is undefined
* Replaces document.addEventListener w/ pkg handling existing ready doc

index.js

@@ -1,6 +1,7 @@
 const history = require('sheet-router/history')
 const sheetRouter = require('sheet-router')
 const document = require('global/document')
+const onReady = require('document-ready')
 const href = require('sheet-router/href')
 const hash = require('sheet-router/hash')
 const hashMatch = require('hash-match')
@@ -61,14 +62,14 @@ function choo (opts) {
     _store.model(appInit(startOpts))
     const createSend = _store.start(startOpts)
     _router = start._router = createRouter(_defaultRoute, _routes, createSend)
-    const state = _store.state()
+    const state = _store.state({state: {}})
 
     if (!selector) {
       const tree = _router(state.location.pathname, state)
       _rootNode = tree
       return tree
     } else {
-      document.addEventListener('DOMContentLoaded', function (event) {
+      onReady(function onReady () {
         const oldTree = document.querySelector(selector)
         assert.ok(oldTree, 'could not query selector: ' + selector)
         const newTree = _router(state.location.pathname, state)