This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
UX: improve messaging so notifications list is far more stable
PERF: improve performance of notifcation lookup queries
- Add feature "SetTransientHeader" that allows shipping info to server
in the next Ajax request
- remove local storage hack used for notifications
- amend lookupStale to return hydrated objects, move logic into store
- stop magically clearing various notifications (likes, invitee accepted, group_summary, granted badge)