Upgrade to Spring Cloud Greenwhich and Spring Boot 2.1 #118

# Conflicts:
#	pom.xml

Improve Micrometer and Grafana integration

Introducing Micrometer Prometheus metric collection

Remove configuration hosted by the Config Server

Add a section about other Spring Petclinic forks

Upgrade to Spring Cloud Finchley SR2 ans Spring Boot 2.0.6

* Add circuit breaker to the getVisitsForPets method

* Use Collections.emptyMap()

* Fallback method with private visibility

* Unit test Hystrix fallback method

* #17 Add a Hystrix Dashboard application

* Fix hystrix-dashboard container name

* Add circuit breaker to the getVisitsForPets method

* Use Collections.emptyMap()

* Fallback method with private visibility

* Unit test Hystrix fallback method

* Introduce assertDescriptionEquals method

* VisitsServiceClientTest refactoring

Readme improvments

* Add alpine jre and dockerize script

* Add docker build argument DOCKERIZE_VERSION

* Increase memory limit

* Use dockerize instead of wait-for-it script

* Update documentation dockerize script

* Remove unnecessary ports

* Revert "Remove unnecessary ports"

This reverts commit a605aaf

* Set memory limit to 512M

* Merge openzipkin

* Remove obsolete links

* Fix honoring memory limits for openzipkin

Fixes #108 | Replace custom Zipkin server with openzipkin