SOL005 - Implementation of additional test steps for checks against NSD and VNFD content in v2.7.1

See merge request !146

# Conflicts:
#   SOL005/VNFPackageManagement-API/VNFPackageManagementKeywords.robot

SOL003 - Implementation of additional test steps for checks against VNFD content in v2.7.1

See merge request !145

SOL002 - Implementation of additional test steps for checks against VNFD content in v2.7.1

See merge request !142

Fix on mockserver configuration (issue #134)

See merge request nfv/api-tests!143

SOL006 reference descriptor file and checking functionality updated (with dashes instead of  underscores)

2.7.1 align fixes

See merge request !140