FIX: force encoding for title field

Job exception: incompatible character encodings: UTF-8 and ASCII-8BIT
--
/var/www/discourse/app/models/search_observer.rb:44:in `update_posts_index'
/var/www/discourse/app/models/search_observer.rb:62:in `index'
/var/www/discourse/app/models/search_observer.rb:89:in `after_save'
...
/var/www/discourse/lib/post_creator.rb:238:in `save_post'
/var/www/discourse/lib/post_creator.rb:72:in `block in create'
/var/www/discourse/lib/post_creator.rb:131:in `call'
/var/www/discourse/lib/post_creator.rb:131:in `block in transaction'
...
/var/www/discourse/lib/post_creator.rb:129:in `transaction'
/var/www/discourse/lib/post_creator.rb:68:in `create'
/var/www/discourse/app/models/topic_embed.rb:40:in `block in import'
...
/var/www/discourse/app/models/topic_embed.rb:33:in `import'
/var/www/discourse/app/jobs/scheduled/poll_feed.rb:39:in `import_topic'
/var/www/discourse/app/jobs/scheduled/poll_feed.rb:33:in `block in import_topics'
/var/www/discourse/app/jobs/scheduled/poll_feed.rb:32:in `each'
/var/www/discourse/app/jobs/scheduled/poll_feed.rb:32:in `import_topics'
/var/www/discourse/app/jobs/scheduled/poll_feed.rb:26:in `poll_feed'
/var/www/discourse/app/jobs/scheduled/poll_feed.rb:16:in `execute'
/var/www/discourse/app/jobs/base.rb:154:in `block (2 levels) in perform'

This exception rise up for correct(!) UTF-8 cyrillic (in my case, but non-latin overall, I suppose) in title field during RSS polling (feed polling url) and breaks topics creation.
So, just force_encoding() makes it work.