* moved regular updates definition to own method to be able to override behaviour in subclass
* moved filter by max entries to own method to be able to override behaviour in subclass
* event type used when firing events to the bus now based on variable to be able to override behaviour in subclass
* feed id introduced instead of url for storing meta-data about the feed to be able to fetch the same feed from different configs with different filtering rules applied
* keep the status of the last update; continue processing the entries retrieved even if a recoverable error was detected while fetching the feed
* added test cases for feedreader component
* better explanation around breaking change
* fixing lint issues and hound violations
* fixing lint issue
* using assert_called_once_with instead of assert_called_once to make it compatible with python 3.5
