CLI: Provide `apply-migrations` command for flask

* main.py: Provide the `apply-migrations` CLI command to run the migrations
  against the auth database.

  The command can be invoked with:

      $ flask apply-migrations

1 files changed, 12 insertions, 0 deletions

diff --git a/main.py b/main.py
index a587697..aaa51da 100644
--- a/main.py
+++ b/main.py
@@ -4,6 +4,18 @@ from gn3.app import create_app
 
 app = create_app()
 
+##### BEGIN: CLI Commands #####
+
+@app.cli.command()
+def apply_migrations():
+    from yoyo import get_backend, read_migrations
+    from gn3.migrations import apply_migrations
+    apply_migrations(
+        get_backend(f'sqlite:///{app.config["AUTH_DB"]}'),
+        read_migrations(app.config["AUTH_MIGRATIONS"]))
+
+##### END: CLI Commands #####
+
 if __name__ == '__main__':
     print("Starting app...")
     app.run()