Let garbage collector do its thing on DOM removal

`Featurette.featurettes` was keeping old references to featurettes alive
even after they'd been removed from the DOM. Keeping those references in
the DOM itself is a slight compromise with the benefit that it lets the
garbage collector collect those instances automatically when a
featurette has been removed from the DOM.
Prevent errors trying to find featurettes that don't exist
Fixing infinite loop issue.
Fixed issues where featurettes calling Featurette.load could cause infinite recursion.
Merge pull request #7 from commondream/recursion-fix

Recursion fix