Bug: Can exit the Windows app without it synchronising before exit.

[andrewcalvin 10]

Reproduce: 

1. edit note

2. File/Quit Evernote

The app quits without synchronising. Edits stay on the local machine only.

Possible fixes: ask user if synchronisation should occur before quitting (should be easy as there should be a dirty flag to show an edit has occurred); or allow manual sync.