Update protos, regenerate code, add examples of usage

build-requirements.txt

examples/collections_client.py

examples/environments.py

examples/items.py

examples/spaces.py

perxis/clients/clients_pb2.py

perxis/clients/clients_pb2_grpc.py

perxis/collaborators/collaborators_pb2.py

perxis/collections_perxis/collections_pb2.py

perxis/common/common_pb2.py

perxis/environments/environments_pb2.py

perxis/invitations/invitations_pb2.py

perxis/items/items_pb2.py

perxis/items/items_pb2_grpc.py

perxis/locales/locales_pb2.py

perxis/members/members_pb2.py

perxis/members/members_pb2_grpc.py

perxis/organizations/organizations_pb2.py

perxis/roles/roles_pb2.py

perxis/roles/roles_pb2_grpc.py