Trigger Change Event before Login

Ref #4651

- Manually triggering the change event ensures compatibility with
legacy password managers and browsers not properly firing events on
autofill (which leads to Ember not picking up the entered values)
Add support for importing images

closes #4608, #4609

- image handler loads in any image files & figures out where they'll get stored
- image importer has a preprocessor which replaces image paths in
  pertinent spots of post, tag and user models
- image importer stores images, keeping the path where it makes sense
- basic test for the preprocessor
Updated meta helpers to use tag meta data if present

No issue

- Tag Meta title and description override default response
- Tag Meta title present on all pages
- Tag Meta description available only on first page
 - Updates tests
Run tag add operations in sequence

Closes #4697
- Run tag add operations in sequence instead of in parallel
  since generateSlug will hand out duplicate slugs until one of
  them is committed to the database.
- Add test.
- Misc cleanup of method parameter names and jshint hints.
Finish tag post count UI.  Misc tag related fixes

Issue #4683
- Finish setting up pagination in tag management page.
- Add post count warning to delete tag modal.  Fix styling.
- Make sure tag input menu is loading all tags.
- Only include saved tags in tag input suggestion list.
- Unload tag records from store when entering tag route so that
  we get accurate post count.
- Add a resetPagination action to pagination-controller-mixin for
  cases where we want to start fresh.
- Include tag.id when sending tag payload to API.
Merge pull request #4693 from cobbspur/metatags

Updated meta helpers to use tag meta data if present
Merge pull request #4698 from jaswilli/tag-dup-slugs

Run tag add operations in sequence
Fix back button on tag UI page

closes #4703

- previous link used absolute url which fails for subdirectories
Merge pull request #4704 from cobbspur/tagsbutton

Fix back button on tag UI page
Merge pull request #4699 from jaswilli/issue-4683

Finish tag post count UI.  Misc tag related fixes
Fixes navigation for Editors on small screen

closes #4707

- Changes Back-link on settings users page to content for editors
Fix modal edge spacing

No issue

The transparent border surrounding modals was being cut off.
This fix uses padding instead of adjusting the left & right valued to create space.
Fix tag mgmt display bugs

- Misaligned header due to back button being in the wrong place in the markup
- Corrected padding on tag delete button
- Updated tag settings input labels for consistency
Merge pull request #4710 from PaulAdamDavis/modal-styling

Fix modal edge spacing
Merge pull request #4711 from JohnONolan/fix-tagmgmt

Fix tag mgmt display bugs
Fix settings back button implementation
Merge pull request #4712 from JohnONolan/fix-backbutton
Merge pull request #4708 from cobbspur/editors

Fixes navigation for Editors on small screen
grunt test task - easily run single test files

no issue
- adds a new grunt test task, which takes a file option representing the path to the test file you want to run
E.g. grunt test --file=unit/config_spec.js OR grunt test --file=integration/import_spec.js
- can run any unit, integration or route task
- can easily be expanded to handle running other tests in future
Merge pull request #4690 from ErisDS/image-importer

Add support for importing images