[PDI-9603] enabling low level support for secure database connections. T...

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three main changes are to allow missing references instead of throwing an
exception, an enhancement of magic aces to allow the exclusion of children
from rules, and finally a shared objects default acl handler which gives
the correct permissions to connections.  Note that a bug was fixed to
allow visibility into the path for the default acl handler.  None of these
capabilities are enabled by default, only in the context of the DI Server
for now.