Add hash code when toString()'ing replication objects to logs.

Enhance debugging to try to diagnose failing test on jenkins machine.
com.couchbase.lite.replicator.ReplicationTest > testPuller[cblite(AVD) - 4.2.2] [31mFAILED [0m
junit.framework.AssertionFailedError
at com.couchbase.lite.replicator.ReplicationTest.testPuller(ReplicationTest.java:530)
Add try/catch with stack trace, seeing NPE in logs on jenkins build machine.

Enhance debugging to try to diagnose failing test on jenkins machine.
com.couchbase.lite.replicator.ReplicationTest > testPuller[cblite(AVD) - 4.2.2] [31mFAILED [0m
junit.framework.AssertionFailedError
at com.couchbase.lite.replicator.ReplicationTest.testPuller(ReplicationTest.java:530)
Enhance debugging to try to diagnose failing test on jenkins machine.

com.couchbase.lite.replicator.ReplicationTest > testPuller[cblite(AVD) - 4.2.2] [31mFAILED [0m
junit.framework.AssertionFailedError
at com.couchbase.lite.replicator.ReplicationTest.testPuller(ReplicationTest.java:530)