Resolve "sp11-Item01: create model manager to register models on the node side"

Closes #157 (closed) Closes #158 (closed) Closes #159 (closed) Closes #160 (closed)

This merge request includes following changes

• Extra section for node's config file named as security for hashing_algorithm, model_approval and allow_default_models.
• Changes in fedbiomed.common.environ to manage configuration file and creating new variables for managing model approval status.
• Adding additional parameters to Fed-BioMed CLI to manage environment variables for model approval purposes.
• Adding register-model and delete-model function to node CLI for registering/approving new models and deleting registered model.
• New table in node database to save model hashes
• New folder envs/development/default_models to keep default models that provided by Fed-BioMed to able to run tutorials.
• ModelManager class to manage, hashing, checksum, registering default models, registering new model etc.
• New request and reply messages to check whether model of the experiment is approved by the nodes.
• New methods for experiment and job to get model file and send request for checking model status.