code tweaks
namespacing uploader
add builder for receipts
abstracted builders
stop being egocentric
removed unused mailbox type
make code more flexible
more flexible builders
Working through the refactor to get all specs to pass
Removed some debugging cruft
Merged upstream changes from master; some changes are suspect - see mailbox_spec.rb:126.
Pulled legacy references to 'RE:' from 'refactoring' branch
Utilize db-based uniqueness filtering with ActiveRecord 4+
Rolled back .distinct in favor of .uniq in Conversation
Rolled back mailbox_spec per @jcoyne's suggestion.
Merge pull request #265 from seth-macpherson/refactoring-fixed-specs

Refactoring fixes
Bump version to 0.12.0.rc2
Bump version to 0.12.0
Pin rspec to 2.99
Due to the newly added namespaces, Mailboxer::Notification's STI type should be migrated from 'Message' to 'Mailboxer::Message'.

Otherwise, when upgrading from 0.11 to 0.12 - existing message will "disappear".