Fix python2 build and add readme (#172)

README.md

@@ -7,6 +7,7 @@ Build:
 [![runnable submodules](https://zasdfgbnm.visualstudio.com/torchani/_apis/build/status/runnable-submodules)](https://zasdfgbnm.visualstudio.com/torchani/_build/latest?definitionId=5)
 [![unit tests](https://zasdfgbnm.visualstudio.com/torchani/_apis/build/status/unit-tests)](https://zasdfgbnm.visualstudio.com/torchani/_build/latest?definitionId=6)
 [![tools](https://zasdfgbnm.visualstudio.com/torchani/_apis/build/status/tools)](https://zasdfgbnm.visualstudio.com/torchani/_build/latest?definitionId=7)
+[![Python2 Inference](https://zasdfgbnm.visualstudio.com/torchani/_apis/build/status/python2?branchName=master)](https://zasdfgbnm.visualstudio.com/torchani/_build/latest?definitionId=11&branchName=master)
 [![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/)

azure/python2.yml

@@ -19,7 +19,7 @@ steps:
   inputs:
     versionSpec: '$(python.version)'
 
-- script: 'azure/install_dependencies.sh && pip install .'
+- script: 'azure/install_dependencies.sh && pip install future && pip install .'
   displayName: 'Install dependencies'
 
 - script: 'python2 examples/energy_force.py'