Re-run links report after updating an edition

If an editor edits an edition that has broken links associated with it,
we automatically re-run the report to check if the broken links have
been corrected.
Tweak wording around link checking
Improve readability of polller javascript
Pin the version of the `typhoeus` gem.

It's pre-1.0, so if this gem is following semantic versioning , it's not
yet in a stable state, so we should pin to a specific version. If it's
not following semantic version (which I'm pretty certain it's not), we
should pin it to a specific version anyway.