This PR aims to begin the pytest implementation process.

• a 'tests/' directory has been included at the repo's root which houses the individual test modules as well as the 'seed_data.yml/json' files.
• conftest.py is a simple test fixture which is meant only to pass down the new MaglaEntityTestFixture objects to the test cases.
• MaglaEntityTestFixture is located at 'magla-repo/magla/test.py' and is responsible for all logic related to start/teardown procedures as well as keeping track of instances for easier memory management during testing.

Objectives for Phase 1:

• test direct CRUD operations with SQLAlchemy session object.
• isolate and test individual sub-entities as far as possible without requiring other magla entities or modules(magla.utils is ok).
• make sure to always compare backend data with seed data used initially.