RSS feed should not generate titles for untitled posts

[AngeloStavrow]

Describe the bug

In generating the feed for a blog, title-less posts are given a pseudo-title that is generated from the beginning of the post body. This is unexpected; title-less posts should have no entry in the <title> property of their feed.

Steps to reproduce (if necessary)

Steps to reproduce the behavior:

1. Create a title-less post in a WriteFreely blog
2. View the feed for this WriteFreely blog (at http://link.to.writefreely.blog/feed)
3. Note that the <title> element of the post created in step 1 has been given a title, based on the beginning of the post's body.

Expected behavior

The <title> element should be empty for the title-less post.