Add global middleware
Move some functions from FlowRouter to FlowRoute

 - Add `_getCurrentRoute` helper
 - Call clientRouter functions from FlowRoute
   - when adding route
   - when setting state
Add route middleware feature
Refactor test names
Fix bugs

 - remove ReactiveDict on server `FlowRoute`
 - fix path errors on package.js
 - fix syntax errors on client flow-route.js
Add tests for `FlowRoute`
Fix `FlowRouter` test

 - make sure tests do not affect outside environment