Fixes 2016 12 21

[dfahlander]

• Bug in rewritten Dexie.getDatabaseNames()
• Added missing properties to typings (d.ts) files of Dexie.d.ts and Dexie.Observable.d.ts.
• Dexie.Syncable: Correction of initial sync handling:
  • Don't await db.syncable.connect() to fulfill or reject each time the local database is opened. If DB has ever been synced with remote, we should rely on the offline state until connection is restablished. No need to halt queries while connecting.
  • Very first time a database connects to a server, we MUST be online and wait for the connect to complete. Assume that the initial sync is essential for the application to function.
• Correction after running various unit tests for the addons:
  • Make sure to never reopen a closed database by accident.
• Dexie.Syncable: Made 'url' index unique as it should be. Existing db's may be needing to increment their version.
• Unit Test framework: Respect custom qUnit checkboxes.
• Dexie bug: When outside a transaction, exception could be thrown instead of returning a rejected promise. This happened if either A) Database had been closed, B) indexedDB API was missing or C) Database had failed to open. Corrected so that a rejected promise is returned instead.
• Dexie: Added db.hasBeenClosed()