Turn `pyrakoon.protocol` into a package
Fix `pyrakoon.client.SocketClient`

Send the prologue to a node after connecting.

(cherry picked from commit cc94836e27e5f4fcd60a7af3977c3200b803bb9a)
Signed-off-by: Nicolas Trangez <ikke@nicolast.be>
Implement some administrative messages
Make `client.SocketClient` slightly more useful

(cherry picked from commit c385d97e0d0b90f60530f46fe8fb830b5799b5c4)
Signed-off-by: Nicolas Trangez <ikke@nicolast.be>