overview-searchbar: Silence a compiler warning

Fallout from 4742182024826482e77c4a50215496488a2090c9

Fixes: https://bugzilla.gnome.org/726165
Notify when indexing remote items takes a long time

When indexing remote items takes more than 10 seconds show an in-app
notification to signal the user we are refreshing our local index.

Original patch from Cosimo Cecchi for gnome-documents.
indexing-notification: Don't queue a check on creation

It is not needed as miners are always started after the notification
manager is created.

Original patch from Cosimo Cecchi for gnome-documents.
embed, notification-manager: Shuffle some code around

This keeps the code in sync with gnome-documents.
indexing-notification: Rename a callback
Add PhotosPrintNotification
print-operation: Plug a memory leak
print-operation: Use the fallback job-name when name is an empty string