Add error template, route and controller

closes #2851

- adds asset paths to ghostPaths as we don't have an asset helper
- sends any invalid routes to 404
Implement Mobile Editor

closes #2957
- add FastClick library to Gruntfile.js
- add touch-editor to client/assets/lib/
- add mobile-specific utils to util/mobile-utils.js
- add codemirror util to set up TouchEditor only if we're really on mobile
- change gh-codemirror from having a default action to a named action. prevents Ember.TextArea firing action on change
- change gh-codemirror `cm.getDoc().getValue()` to `cm.getValue()` for portability
- change codemirror-shortcuts ES6 export/import style
- changed ghostimagepreview.js to check for Ember.touchEditor in addition to Ghost.touchEditor
Mobile Interactions

closes #3018
- split clientold mobile interactions into their respective Ember routes/views
- create PostsView and SettingsView with mobile interactions
- place interactions for the publish bar into ApplicationRoute on init
Merge pull request #3050 from darvelo/mobile-editor

Implement Mobile Editor
Merge pull request #3055 from darvelo/mobile-interactions

Mobile Interactions
Merge pull request #3052 from ErisDS/issue-2851

Add error template, routes and controller
Set edit post shortcut to 'enter'

closes #2308
Finish Debug screen for Ember admin

Closes #2847
Merge pull request #3091 from jaswilli/debug

Finish Debug screen for Ember admin
Allow tabbing responsive editor when not on mobile.

fixes #3095
- Add `click` event to floatingheader
Merge pull request #3098 from halfdan/3095-non-mobile-tabbing

Allow tabbing responsive editor when not on mobile.
Stay on posts.index route when no posts exist

No Issue
Merge pull request #3104 from jaswilli/route-undefined

Stay on posts.index route when no posts exist
Add off as a noop function to touch editor.

Closes #3107
Merge pull request #3108 from novaugust/touch-editor-off

Add off as a noop function to touch editor.
Close notifications on user action properly.

fixes #3105, refs #3012
- Add additional closeAll() calls where users interact with data
Change text on leave modal cancel button

issue #3106
Show correct post notificatons based on status.

closes #2850
- Add messageMap from old admin
- Add two methods to pick the correct notification based on prev status and current status
Update Ghost-UI version to 0.8.1

References #3102 #2491
Merge pull request #3116 from PaulAdamDavis/master

Update Ghost-UI version to 0.8.1