Increase test coverage to 80%

[rhinof]

test coverage as reported by coveralls should be at least 80%

[rhinof]

quick wins:

• remove leftover methods from builder interface and implementation will increase coverage #34
• add simple unit tests to policies (ttl, durability)
• Add unit test for bus builder that validates the ConfigureHealthChecks sets values properly on the builder
• Set integration tests to configure bus to run with multiple workers

Not so quick wins but needed:

• Test protobuff and avro serializers (@vladshub )
• Test RPC calls from with in a Saga
• Test transactional outbox scavenging capabilities
• Test error scenarios of Glue component