add post_moveToTrash and post_restore signals to the trash bin

This patch added a post_restore and post_moveToTrash signal to the trash bin app.

This enables other apps to react on it and perform its own  actions  to preserve and restore informations.

The signal class is '\OCA\Files_Trashbin\Trashbin'
The signals are 'post_moveToTrash' and 'post_restore'
Both signals contain the parameter $path with the path of the moved/restored file.

This should provided everything which is needed in #1431