Allow deep vs shallow replication options

Users of replication should have a way to choose whether to replicate a node

• deep: including all its subtree
• shallow: including just he node properties

Typically an user editing content visually will trigger a replication of only the edited content (shallow).
However an user importing a lot of content will trigger a deep replication after all content is imported.

Shallow replication is more targeted and produces the least changes in the system and it is probably best fitted to be the default replication option.