Allowing multiple-URL parsing for REST calls

This is still probably not the 'correct' way to do this parsing, but since we don't get valid JSON dumped into the text field, I'm not sure of a better way right now. If there's a good way for our input plugin to generate JSON, that might be better.

However, this should handle both lists dumped by our YAML parsing as well as human-input lists of URLs.
It'll... break on any unescaped URLs, which is bad.

Also, how do I write unit tests for this module? I feel like I need to go wash away my shame, opening a pull request without test code.