prompt a user to save his changes before closing a tab in NWK
Merge branch 'Reach' of https://github.com/pboyer/flood into close-tab

Conflicts:
	app/scripts/models/UnsavedWorkspaceChangesHandler.js
Merge pull request #100 from marimano/close-tab

REACH-119 Ask about saving unsaved changes before close a tab in NWK