Merge pull request db-migrate#599 from xcorail/master

Add LGTM code quality badges

Author: wzrdtales

README.md

@@ -3,6 +3,8 @@
 [![Dependency Status](https://david-dm.org/db-migrate/node-db-migrate.svg)](https://david-dm.org/db-migrate/node-db-migrate)
 [![devDependency Status](https://david-dm.org/db-migrate/node-db-migrate/dev-status.svg)](https://david-dm.org/db-migrate/node-db-migrate#info=devDependencies)
 [![Documentation Status](https://readthedocs.org/projects/db-migrate/badge/?version=latest)](https://readthedocs.org/projects/db-migrate/?badge=latest)
+[![Code Quality: Javascript](https://img.shields.io/lgtm/grade/javascript/g/db-migrate/node-db-migrate.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/db-migrate/node-db-migrate/context:javascript)
+[![Total Alerts](https://img.shields.io/lgtm/alerts/g/db-migrate/node-db-migrate.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/db-migrate/node-db-migrate/alerts)
 
 # db-migrate