Add LGTM status (#147)

README.md

@@ -7,6 +7,7 @@
 [![tools](https://zasdfgbnm.visualstudio.com/torchani/_apis/build/status/tools)](https://zasdfgbnm.visualstudio.com/torchani/_build/latest?definitionId=7)
 [![CodeFactor](https://www.codefactor.io/repository/github/aiqm/torchani/badge/master)](https://www.codefactor.io/repository/github/aiqm/torchani/overview/master)
 [![codecov](https://codecov.io/gh/aiqm/torchani/branch/master/graph/badge.svg)](https://codecov.io/gh/aiqm/torchani)
+[![Total alerts](https://img.shields.io/lgtm/alerts/g/aiqm/torchani.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/aiqm/torchani/alerts/)
 
 TorchANI is a pytorch implementation of ANI. It is currently under alpha release, which means, the API is not stable yet. If you find a bug of TorchANI, or have some feature request, feel free to open an issue on GitHub, or send us a pull request.