This change both speeds up specs (less strings to allocate) and helps catch
cases where methods in Discourse are mutating inputs.
Overall we will be migrating everything to use #frozen_string_literal: true
it will take a while, but this is the first and safest move in this direction
* SPEC: PollFeedJob parsing atom feed
* add FeedItemAccessor
It is to provide a consistent interface to access a feed item's tag
content.
* add FeedElementInstaller
to install non-standard and non-namespaced feed elements
* FEATURE: replace SimpleRSS with Ruby RSS module
* get FinalDestination and download with Excon
* support namespaced element with FeedElementInstaller