Fixes clipboard for Rails 4.1
Starting in Rails 4.1, Marshal is no longer used to serialize cookie values and the new format is JSON-based (http://edgeguides.rubyonrails.org/upgrading_ruby_on_rails.html#cookies-serializer). Because the format is based on JSON, all Hashes get their keys stringified. This will automatically create a new clipboard for a broken session containing a string such as  or a clipboard stored with an existing cookie.
Merge pull request #548 from paperculture/fix-clipboard

Fixes clipboard for Rails 4.1