Add LGTM.com code quality badges (#680)

Author: xcorail

README.md

@@ -8,6 +8,8 @@
 [![PayPal donate button](http://img.shields.io/paypal/donate.png?color=blue)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=64CCN9JJANZXA "Help this JSqlParser version using Paypal")  
 
 [![Gitter](https://badges.gitter.im/JSQLParser/JSqlParser.svg)](https://gitter.im/JSQLParser/JSqlParser?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge)
+[![Code Quality: Java](https://img.shields.io/lgtm/grade/java/g/JSQLParser/JSqlParser.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/JSQLParser/JSqlParser/context:java)
+[![Total Alerts](https://img.shields.io/lgtm/alerts/g/JSQLParser/JSqlParser.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/JSQLParser/JSqlParser/alerts)
 
 Look here for more information and examples: https://github.com/JSQLParser/JSqlParser/wiki.