NFV&MEC Plugtests 2020: fixes of issues found during Plugtests

SOL002/VNFConfiguration-API/ApiVersion.robot

SOL002/VNFConfiguration-API/Configuration.robot

SOL002/VNFConfiguration-API/SOL002-VNFConfiguration-API.json

SOL002/VNFConfiguration-API/SOL002-VNFConfiguration-API.yaml

SOL002/VNFFaultManagement-API/Alarms.robot

SOL002/VNFFaultManagement-API/ApiVersion.robot

...NFFaultManagement-API/EscalatePerceivedSeverityTask.robot

SOL002/VNFFaultManagement-API/IndividualAlarm.robot

SOL002/VNFFaultManagement-API/IndividualSubscription.robot

...VNFFaultManagement-API/SOL002-VNFFaultManagement-API.json

...VNFFaultManagement-API/SOL002-VNFFaultManagement-API.yaml

SOL002/VNFFaultManagement-API/Subscriptions.robot

SOL002/VNFFaultManagement-API/environment/variables.txt

SOL002/VNFIndicator-API/ApiVersion.robot

SOL002/VNFIndicator-API/IndividualSubscription.robot

SOL002/VNFIndicator-API/SOL002-VNFIndicator-API.json

SOL002/VNFIndicator-API/Subscriptions.robot

SOL002/VNFIndicator-API/VNFIndicators.robot

SOL002/VNFIndicator-API/VnfIndicatorsInVnfInstanceId.robot

SOL002/VNFLifecycleManagement-API/ApiVersion.robot