remove ghost.settings and ghost.notifications

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
Gruntfile cleanup

issue #1340

- remove old weekly and nightly builds and associated stuff
- add help task
- add more documentation / comments
Merge pull request #1627 from sebgie/issue#755

remove ghost.settings and ghost.notifications
Merge pull request #1626 from ErisDS/grunt

Gruntfile cleanup
Reverting express-hbs to 0.5.1

- there is some sort of bug with 0.5.2 when combined with recent changes which results in the following error:

/home/travis/build/TryGhost/Ghost/node_modules/express-hbs/lib/hbs.js:128
      if(count < self.partialsDir.length){
                                 ^
TypeError: Cannot read property 'length' of undefined