* Add security check in AgencyComm::sendWithFailover.
* some cleanup
* added some more tests
* add typeName() to AgencyCommTransaction to make the transaction type printable in debug messages
* improve debuggability
* Return connection timeout condition as being same as aborted operation. Otherwise ClusterCommResult::fromError() will mark sendWasComplete as true.
* make test of connect_time specific to the TIMEOUT error
* Take out 503 timeouts altogether.
* Overhaul of AgencyComm::sendWithFailover loop.
* Let performRequests optionally ignore 404 coll not found.
* Fix error message "database not found" when AgencyComm failed.
* Add log entries in Agency if locks are acquired too slowly.
* Reexecute the javascript cluster sync stuff even if there was no plan/current change...So failed sync jobs can retry later...
* Cover callbacks in Communicator by lock. This fixes https://github.com/arangodb/planning/issues/370
* Put in delay in waiting for leader in agency test.
* Schmutz logging to heartbeat topic.
* Add more lock time diagnostic in agent.
* Switch on agencycomm tracing in coordinator.