Only show edition problems if not state related.
Get rid of slightly confusing warning message.
Allow mailto and anchor links in markdown.
Copy change on link checker notices.
Fix incorrect regex syntax in link checking.
Merge pull request #1043 from alphagov/basic-validation-for-markdown-links

Fixes to validation for markdown links

https://www.pivotaltracker.com/story/show/60397572
https://www.pivotaltracker.com/story/show/60397200