Describe server <-> library communication

[vitaliimelnychuk]

As an example here https://github.com/melnychukvitaliy/mysql-migrate we've used simple https://github.com/db-migrate/node-db-migrate library to manage migration and percona toolkit to run them

We need our interface on how API will communicate with migration libraries (knexjs, db-migrate,..)

Here are the main concepts we need from the library:

• unique migration number
• migration command interface -> should be run in crispy-worker where we have database connection
• library commands to register migrations. For example, publish -> store migration in our database and show in crispy-web