Integrate with tng-sdk-validate

[mpeuster]

If validator is installed, use it.

• [x] install validator in Docker image (have it always there in service mode)
• [x] have a command line flag to manually skip validation
• [x] implement validation as such
  • [x] validate during packaging
    • [x] good case tng-pkg -p misc/5gtango_ns_project_example1/
    • [x] bad case tng-pkg -p misc/5gtango_ns_project_example1_bad/
    • [x] nice error handling
    • [x] add unittest
  • [x] validate during unpackaging (inside Docker!!!!) (problem: we do not always unpackage to a tng-project! solution: run a second project sotrage backend always that unpacks to tmp and validates there)
    • [x] good case tng-pkg -u misc/5gtango-ns-package-example.tgo -o /tmp
    • [x] bad case tng-pkg -u misc/5gtango-ns-package-example-bad.tgo -o /tmp
    • [x] add unittest
• [x] check that old validation is not called anymore (or keep it as fallback)

Implement/wrap in validation.py

[mpeuster]

https://github.com/sonata-nfv/tng-sdk-project/issues/59

[mpeuster]

Service validation:

tng-validate -i --service /var/folders/yx/lvxqrl7j7954pkz6mmsh72br0000gn/T/tmpebt55o2w/Definitions/mynsd.yaml --dpath /var/folders/yx/lvxqrl7j7954pkz6mmsh72br0000gn/T/tmpebt55o2w/Definitions/ --dext yml