Develop codacy test (#1667)

* fixed the test break on pytest > 4.0, added the pytest cov

* added the pytest-cov package

* added the logic to upload coverage.yml report to codacy

* remove the warning message in during the pytest

* added the codacy badge to show what it looks like

* added a space

* removed the space

* removed the duplicate pytest

* removed the extra spaces

* added the test coverage badge

* point the badge to the test branch

* changed

* moved the python test coverage to circleci

* removed the badge

* added the badge

* fixed the link

* Added the gym_unity test to the circleci

* Fixed the gym_unity installation

* Changed the test-reports from the ml-agents subfolder to the root folder, so that it covers gym_unity’s pytest also

.circleci/config.yml

             python3 -m venv venv
             . venv/bin/activate
             cd ml-agents && pip install -e .
+            pip install pytest-cov==2.6.1 codacy-coverage==1.3.11
+            cd ../gym-unity && pip install -e .
 
       - save_cache:
           paths:
       - run:
-          name: Run Tests
+          name: Run Tests for ml-agents and gym_unity
-            cd ml-agents/ && pytest tests/
-            pytest --junitxml=test-reports/junit.xml
+            pytest --cov=mlagents --cov-report xml --junitxml=test-reports/junit.xml -p no:warnings
+            python-codacy-coverage -r coverage.xml
-          path: ml-agents/test-reports
+          path: test-reports
-          path: ml-agents/test-reports
-          destination: ml-agents/test-reports
+          path: test-reports
+          destination: test-reports

README.md

 <img src="docs/images/image-banner.png" align="middle" width="3000"/>
 
 # Unity ML-Agents Toolkit (Beta)
+[![docs badge](https://img.shields.io/badge/docs-reference-blue.svg)](docs/Readme.md)
+[![license badge](https://img.shields.io/badge/license-Apache--2.0-green.svg)](LICENSE)
 
 **The Unity Machine Learning Agents Toolkit** (ML-Agents) is an open-source
 Unity plugin that enables games and simulations to serve as environments for