Switch to RailsGravatar

[rickychilcott]

This addresses #880 which is a concern about relying on the rb-gravatar gem, which has been GPLed in sn/ruby-gravatar@5a1225c We could peg our dependency on an older version of the gem, but it might be better to rely on a gem that is guaranteed to not be GPLed.

As such, I created a gem called RailsGravatar which has a very similar API but changes some of the internals to better output rails tags (using ActionView helpers) and wrote a comprehensive test suite. The most important part is that it's MIT licensed and has no concerns about it being GPLed.

[glebm]

Thanks!

[glebm]

Looks like this isn't working correctly (CI failing)

The 3rd argument to rb-gravatar's src was 'mm' but RailsGravatar expects a URL?

Can you please send a PR fixing this?

[glebm]

Looking at the source, it's not the fallback_image_url; not sure what the issue is

[glebm]

Example failing job https://travis-ci.org/github/thredded/thredded/jobs/766574511

Error:

   Failure/Error: <%= image_tag post.avatar_url, class: 'thredded--post--avatar' if post.user %>

      ActionView::Template::Error:

        nil is not a valid asset source

[timdiggins]

@rickychilcott we can't reopen this PR because it was merged once, but can you open another PR for this when you're ready?