Issue with content-available in using Grocer::Server

Here's a failing test case for this issue:

When testing notifications, Grocer::NotificationReader instantiates a new Grocer::Notification from the payload sent to it by Grocer::Pusher. Because I change :content_available to :'content-available', this ends up causing a NoMethodError in the server process. How do you think I should fix this? The option that feels best to me, though still kinda clunky, is for Grocer::NotificationReader to modify the hash key before passing it to Grocer::Notification.new.