Implement prompt method for console
Create Before Sync method on watcher

So that account and app watchers can have different behaviors.
Implement workspace retrieval in GalleryClient
Allow file system to compute local file states
Implement conflicts identification in account watcher
Enable user to decide what to do with file differences

Fixes #17.
Implementa resolução de conflitos com arquivos remotos
Take out of ChangeQueue the responsibility of getting change content
Permite resolver conflitos com dados locais
Corrige normalização de quebras de linha