There are people who have RSS feeds set up that do HTTPS -> HTTP
redirects which throw errors. Since RSS feeds are all configured
by admins I think it's OK if they allow an unsafe redirect as the
content is public anyway. This will reduce many server side errors.
SimpleRss is unreliable with parsing RSS feeds that contain German Umlauts.
For example this feed http://www.lauffeuer-lb.de/api/v2/articles.xml can't be
parsed by SimpleRss. Discourse's logs are full of
```
Job exception: Wrapped Encoding::CompatibilityError: incompatible character encodings: ASCII-8BIT and UTF-8
Job exception: incompatible character encodings: ASCII-8BIT and UTF-8
```
The embedding fails because the feed can't be parsed.
This change forces the encoding (using #scrub) which prevents the numerous
encoding errors.
Feature to allow each imported post to be created using a different discourse
username. A possible use case of this is a multi-author blog where discourse
is being used to track comments. This feature allows authors to receive
updates when someone leaves a comment on one of their articles because each of
the imported posts can be created using the discourse username of the author.
