Moving functions, use more consistent naming scheme for manipulating counters
Making userlog updates optional on save
Don't sign *Logs at save, only at sync.  Other objects, sign right away.
Moving DeferredSignSyncedModel into securesync, applying to Facility* models
Make transacting on generaterealdata an option, not the default.
Move serialize/deserialize into securesync.engine.
Cleaning code after self-review, fixing a bug in poorly-conceived demo code; now uses real logic! :P
Locally save changes made during syncing--but avoiding save machinery.

Conflicts:
	kalite/securesync/engine/__init__.py
fixing broken migration
Migrate to method that works for SyncSession
Merge branch 'develop' of github.com:learningequality/ka-lite into signing_at_sync

Conflicts:
	kalite/control_panel/views.py
	kalite/main/models.py
Merge pull request #748 from bcipolli/signing_at_sync

Raspberry Pi: Cryptographically sign records when syncing, not when saving