fixes#1575
- Moves most code that was in ghost.js into ./core/server/index.js
- Creates ./core/server/config/theme.js to hold all theme configurations
(which previously lived on ghost.blogGlobals())
- Removed ghost.server, passing it in as an argument where needed
and allowing middleware to hold onto a reference for lazy use.
covers 90% of #755
- moved ghost.settings to api.settings
- moved ghost.notifications to api.notifications
- split up api/index.js to notifications.js, posts.js, settings.js,
tags.js and users.js
- added instance.globals as temp workaround for blogglobals (Known
issue: blog title and blog description are updated after restart only)
- added webroot to config() to remove `var root = ...`
- changed `e` and `url` helper to async
- updated tests