test(mm_bot): add tests for the persistence layer of the mm_bot

[santiagohirsch]

Should add tests for all DAOs in the persistence layer of the mm-bot:

• All tests should be in the tests folder within the mm-bot
• The local database for testing should have default inserts using sql scripts
• The tests should follow the following workflow: setup local db (before all) -> populate the local db (before each) -> clean the local db (after each) -> teardown the local db (after all)