This makes clear that it is possible to have more than one connection
to/from a given node. Most obvious case is election, where all masters
try to connect with each other.

Deprecate getConnectionByUUID.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@1600 71dcc9de-d417-0410-9af5-da40c76e7ee4