Add topn option

Add "show_topn"  and try find image from summary filed (#20)

* Add a Configuration variables "show_topn", it's disabled when
show_topn > number of rss entries

* Update README.md

* when inclusions contains image option, it will try to find image within
summary filed if image not found

* blank lines modified

Display entries as a list

Note: This is a breaking change for the https://github.com/custom-cards/list-card
I don't have an expected date on when I'll get around to fixing it. If you're using the list-card, do not upgrade to 0.0.8 for now.

preserve timezone info for dates

0.0.7

entries as list (#19)

Rename sensor.feedparser to feedparser

0.0.6

entries as list (#19)

Create resources.json

Create resources.json (#14)

* Create resources.json

* move manifest.json

* version bump

v0.0.2

Fix Typo (#9)