Extension for jsonlibrary in case of python3. Small fixies. SOL005 completed

...2/VNFLifecycleManagement-API/jsons/operateVnfRequest.json

...tNotification-API/jsons/ThresholdCrossedNotification.json

...3/VNFLifecycleManagement-API/jsons/operateVnfRequest.json

SOL003/VNFPackageManagement-API/VNFPackageArtifacts.robot

SOL003/VNFPackageManagement-API/jsons/subscriptions.json

SOL003/VNFPerformanceManagement-API/IndividualPmJob.robot

...tNotification-API/jsons/ThresholdCrossedNotification.json

SOL005/NSDManagement-API/IndividualNSDescriptor.robot

SOL005/NSDManagement-API/IndividualPnfDescriptor.robot

SOL005/NSDManagement-API/IndividualSubscription.robot

SOL005/NSDManagement-API/NSDContent.robot

SOL005/NSDManagement-API/NSDManagementNotification.robot

SOL005/NSDManagement-API/NSDescriptors.robot

SOL005/NSDManagement-API/PNFDContent.robot

SOL005/NSDManagement-API/PNFDescriptors.robot

SOL005/NSDManagement-API/Subscriptions.robot

.../NSDManagement-API/environment/individualSubscription.txt

SOL005/NSDManagement-API/environment/nsDescriptors.txt

SOL005/NSDManagement-API/environment/pnfDescriptors.txt

SOL005/NSDManagement-API/environment/subscriptions.txt