Optional project_groups for project creation, wip

NC-247
project_groups field added to project create serializer (nc-247)
PGM can create only projects with his groups (nc-247)
test that project is created with given groups (nc-247)
Merge branch 'develop' of code.opennodecloud.com:nodeconductor/nodeconductor into feature/nc-247
ensure that project was deleted or created in tests (nc-247)
Merge branch 'feature/nc-247' into 'develop'

Feature/nc 247 (project can be created with project groups)