Tls support (#28)

* Adding support for amqp tls connections

* Correcting spacing in the config.go file

* Checking what travis ci gives as a docker version

* Working around a docker-compose bug that prevents  empty defaults

* removed docker-compose version check

This was being used for debugging a build failure and is no
longer needed

* Making a rabbit mq connector that should be more testable in theoryr

* Refactors and initial tests around CreateConnector

- Added ginkgo and gomega for testing
- Test that a connector of the correct type is created
- Moved the instantiation of the connector into mapping.go
- Added a test to mapping.go to assert that the created connector is non nil
- Renamed config on TlsRabbitConnector to config to reduce confusion around
  the config package

* Adding some happy case tests

* Removed some debug calls that were added by accident

* Adding more test coverage

* Adding test coverage around the tls connector

* Switch to using HasPrefix and add additional test coverage around the basic connector

Merge pull request #30 from AirHelp/bump-up-go

Bump up Go to 1.11.0 & alpine to 3.8

Using go dep (#26)

* Using go dep

* Separate dependecy and application docker layers

* Empty line