Sync Manager for iOS (work in progress)

Half-way there - but it's probably best to get review/feedback early

- projects dependencies updated
- plugin mostly implemented (in some cases calling methods that don't do anything yet, no events fired in webview yet for sync updates)
- sync down implemented for soql targets (sync status is updated in database but no notifications sent out yet)
- sync up: not started
If this is a user-centric class, then the user should be passed through to SmartStore as well: `[SFSmartStore sharedStoreWithName:user:]`