Change autolinked URLs to output nice quotes

ref #4257

- This is a follow on from #4257 where I updated the codestyle.
- We were outputting escaped single quotes when double quotes would be much nicer.
- Changes the HTML output from our markdown conversion (non-breaking change)
- Updated tests to match the new output
Upgrading Casper to 1.1.1
Merge pull request #4280 from ErisDS/gfm

Change autolinked URLs to output nice quotes
Cancel pending auto-save if manual save occurs

Closes #4309
Peg ember-template-compiler to 1.7.0

Closes #4310
- Ember-template-compiler introduced a breaking change in
  1.9.0-alpha. We're using it via grunt-ember-templates.
Merge pull request #4313 from jaswilli/issue-4309

Cancel pending auto-save if manual save occurs.
Ensure slug generation has completed prior to save

Refs #4307 Refs #4259
- Make sure that a slug has been generated prior to the first
  save that occurs on a post.
- Wait on in-flight slug generation requests before saving.