Metacat

Return the new pid (not the obsoleted pid) on update(), and set the correct system metadata.

include Mock version of looking up the base url for our own node - for testReplicate().
still expecting a failure during MN.replicate() since we are trying to add the replica to the same MN from which it came.

allow alternative CNode implementations (subclasses) to be returned when D1Client.getCN() is called. The alternative is given in the Settings configuration via the D1Client.cnClassName property.
MockCNode in Metacat is an example of such an alternative and is used when Metacat requires methods of a CN be present for unit testing.

Test that the obsoletes and derivedFrom system metadata fields were set correctly.

use objectFormatIdentifier for listObjects()
remove provisional system metadata indicator - Metacat will not implement reserveIdentifier()

add test for synchronization failed -- TODO: verify that the log record made it in the logs

provisional replicate() implementation -- does not check if the session's subject is "allowed" to do this.
the test also requires 2 servers -- right now it attempts to replicate with itself which will fail because of duplicate IDs

provisional version of getOperationStatistics() -- not clear if we are meant to aggregate by hour or by day

include test for replicate() method -- still fails as not implemented

allow null objects (use default checksum)