Added Alembic for migrations

migrations/script.py.mako

@@ -0,0 +1,25 @@
+"""${message}-
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+"""
+import sqlalchemy as sa
+from alembic import op
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+branch_labels = ${repr(branch_labels)}
+depends_on = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    """Perform the upgrade."""
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    """Perform the downgrade."""
+    ${downgrades if downgrades else "pass"}