Scroll post-item-view into view

Closes #3998
- Scroll the active post into view on page load
- If the active post changes and the newly active post is offscreen, scroll it into the middle of the screen
Update downsize node module. Small test updates.

issue #4017
- downsize 0.0.5 -> 0.0.8
- downsize is now better at punctuation, update {{content}} and {{excerpt}} tests appropriately.

Conflicts:
	package.json
Adds complete url for Sitemap in robots.txt

closes #4589

- Adds {{blog-url}} to robots.txt
- Replaces {{blog-url}} with blog.url from config
Merge pull request #4639 from cobbspur/robots

Adds complete url for Sitemap in robots.txt
Fixes sitemap image errors

closes #4591

- switches to using author cover image
- adds a protocol of http if using a protocol relative url
Merge pull request #4552 from zethraeus/master

Update downsize node module. Small test updates.
Merge pull request #4346 from novaugust/scroll-posts

Scroll post-item-view into view
Merge pull request #4636 from cobbspur/sitemap

Fixes sitemap image errors
Test update to handle downsize improvements

no-issue

- downsize is now better at white space and punctuation
Add view post link on published and updated posts

closes #1756

- adds a post url link to 'post updated' and 'post published' in editor
- adds join function in ghost paths
- adds a '/' detection to makeRoute method
- adds test for join function
Fixed editor tag field handling of comma key on international keyboards

fixes #4356
- Added new keyPress event handler to identify keys by character instead of key
- Removed code for handling comma key from keyDown event handler
Merge pull request #4645 from katiefenn/issue-4356
Merge pull request #4629 from cobbspur/postpreview

Add view post link on published and updated posts
allow re-login when authorization fails on editor.edit route
Fixup behavior and styling of editor re-auth.

Closes #2092
- Adds styling for re-auth modal.
- Prevent transition to posts route on success.
- Clear credentials from controller.
- Handle confirmAccept action if form is submitted via 'enter'.
- Only allow re-auth as the user that was previously logged in.