Admin isn't shown "make owner" option

closes #3558
- Replaced canAssignRoles as "show user" conditional with new
"canMakeOwner"
Descriptive error if user by mail not found.

closes #3537
- Replaced generic NotFound error with descriptive NotFoundError.
Merge pull request #3561 from felixrieseberg/iss3558

Admin isn't shown "make owner" option
Merge pull request #3521 from jaswilli/notifications

Prevent stacking of notifications
Merge pull request #3560 from felixrieseberg/iss3537

Descriptive error if user by mail not found.
Update Ghost-UI with grunt init

Closes #3554

- Adds a shell command to update Ghost-UI
Show "Make Owner" only if displayed user is admin

closes #3570
- Added ‘controller.user.isAdmin’ as an condition for displaying the
“make owner” option
Ensure keyboard navigation matches custom post sorting.
Small performance tweak for Posts ordering.

* Move publishedAtCompare to standalone function in closure scope
  (allows better browser optimizations).
* Avoid getting the same field (published_at) more than once.
Error modifying "author" attribute before post record has been created

fixes #3523
- when changing the author, added a check to NOT trigger a save if the post has not been created/saved as yet
fix most recent post stolen by the last logged in user AND only show active users in post-settings-menu drop-down

fixes #3549 fixes #3528
- instead of grabbing and setting the author after fetching the list of users, get the author info from the models "author" property and set it when that value returns. (3549)
- added filter to the PSM's "authors" attribute to only display active users (3528)
Stop event propagation when hitting "enter" in the gh-blur-input component

fixes #3516
- new behavior is disabled by default
- added new stopEnterKeyDownPropagation property enable new behavior
Replacing "touch start" with "tap" event, provided by hammer.js

fixes #3502
Insert inline code shortcut for editor

closes #3543
- Wired up existing code shortcut in codemirror-shortcuts.js in
editor-shortcuts.js
Merge pull request #3562 from PaulAdamDavis/3554-update-gui

Update Ghost-UI with grunt init
Merge pull request #3572 from rwjblue/fix-keyboard-nav-for-posts

Ensure keyboard navigation matches custom post sorting.
Merge pull request #3574 from rwjblue/speed-up-posts-orderby

Small performance tweak for Posts ordering.
Autofocus on input fields after routing

closes #3538, closes #3541
- The “autofocus” property isn’t considered by browsers if the element
is created after the page has been loaded. The Ember cookbook
recommends extending the input type with a manually triggered
autofocus, which I included here.
- This introduces the new helper “gh-focus-input”, an input field
gaining focus even when routing occurs.
Merge pull request #3571 from felixrieseberg/iss3570

Show "Make Owner" only if displayed user is admin
Merge pull request #3535 from rwjblue/properly-transition-on-mobile

Handle toggleing the content screen on mobile.