Revise README and do pre-release preparations for 0.2.0 release

[ogajduse]

• change the example config
• use bumpver to bump all version strings
• revise badges
• add button "Add to HA"
• pubDate -> published PubDate gone? #101
• document how to configure multiple feeds more than one feed_url #102
• advise users to use image instead of enclosure
• document Feedparser not pulling description attribute entry #130