support labels

[TristanHorlamus]

Issue Description

missing ability to use label
https://docs.spring.io/spring-cloud-config/docs/current/reference/html/

Steps to Reproduce

the GetConfiguration method does not accept label as 3rd parameter and therefore won't be able to build a path to call SCC with a specific label as shown on spring cloud config documentation:
/{application}/{profile}[/{label}]

suggestion is to introduce a second function (to be backward compatible) GetConfigurationWithLabel that allows for a 3rd parameter to be used and added at the end of the path

Expected Behavior

calling GetConfiguraitonWithLabel will apply the provided label and pull the spring cloud config from the selected label (branch-name / tag)

Acceptance Criteria

[Piszmog]

Closed by #68