NodeSelection struct is used to make decisions (and assertions) related to node selection.
Usually we don't use email and wallet for placement decision, as they are not reliable.
But there are cases, when we know that the email address is confirmed. Also, it can be used for upper-bound estimations (if same wallet is used for too many pieces in a segment, it's a sign of a risk, even if not all the risks can be detected with this approach, as one owner can use different wallets).
Long story short: let's put wallet and email to the SelectedNode.
Change-Id: I922185e3769d43eb7762b8d60d88ecd3d50991bb
6304046e80