Add tests for handlebars core helper functions

Closes #1842
-add unit tests for core helper functions
-fix up coreHelpers.e
-clean up coreHelpers.pagination
Make cache max-age on theme assets one year.

closes #2790
- Added one year in ms var.
- refs: #2447
[docs] absolute=true will add options.hash

Ran into this will calling the helper from a theme, tried to get the absolute url, but just providing {{url absolute}} wasn't enough. After explicitly adding `=true` it worked.
fix mirrored scrolling in markdown editor

issue #2426
- ember markdown component now looks for preview element as a DOM ancestor rather than a descendent
[fix] always add quotes
Merge pull request #2794 from Swaagie/patch-1

[docs] absolute=true will add options.hash
Merge pull request #2788 from jaswilli/issue-1842-tests

Add tests for handlebars core helper functions
Merge pull request #2791 from shindakun/assetcache

Make cache max-age on theme assets one year.
Implement signup in Ember

Closes #2410

- Add signup action that posts to signup endpoint
- Fix nav bar showing on signup page
- Fix image link when a user hasn't set their image yet
- Redirect to the ember/signin page if requesting an ember page
Fix content preview actions and add tests

Closes #2798
-fetch full model for active post in Backbone content preview view
-remove unnecessary type check in Models.Post.saving
-add functional tests for all post settings menu actions in editor screen
-add functional tests for all post actions in content preview
 screen for posts with and without tags
Improve status codes

closes #2187
- added UnsupportedMediaTypeError (code: 415)
- added status code 201 if a new object was created
- Updated tests
Add ghostPaths util and initializer

No Issue

- Move the ghostPaths from base model to utils
- Add initializer that injects it into every route, model and controller
- Add a adminUrl and apiUrl helper method
Merge pull request #2768 from jgable/emberPaths
Merge pull request #2754 from sebgie/issue#2187

Improve status codes
correct settings.edit call signature for installedApps

closes #2773

- this is left over from my refactoring work
Merge pull request #2801 from ErisDS/issue-2773

correct settings.edit call signature for installedApps
Merge pull request #2780 from jgable/ember-signup

Implement signup in Ember
Merge pull request #2795 from appleYaks/fix-editor-scroll

fix mirrored scrolling in markdown editor
Merge pull request #2799 from jaswilli/issue-2798

Fix content preview actions and add tests
Ember editor save and publish button functionality

Closes #2747
- Added new 'editor-save-button' view and template.
- Added save action to post controller.
- Set a new post as the default model for the /editor/ route.
- Set the `posts/post` controller as the controller for the /editor/
  route.
- Needs ghost-popover #2418 component for full pop-up functionality