Added watcher cancellation to avoid spurios messages when collection is deleted
Fixed test framework. Fixed racing condition in leader state manager. Fixed bug in update log initialisation.
Merged version replication. Ported version replication tests to new test framework.
Improved documentation
Merge pull request #8 from sindicetech/cdcr-22

Cdcr 22
Merged with solr6273
Finalised update log synchronisation