Move redirects and error handlers to the last items set up

Currently redirects and errors handlers are added before custom routes.  This causes statics to return 404.  

I moved them to after `events.onMount`. 

 I found this from creating a module to use keystone.  I could do create everything I wanted using
```
keystone.start({onMount:function() {  mymodule.add() } });
```
except add statics.