feat(py3/py27): integrate pytest-html

templates/tests/py27.yml

 ---
 py27:
   before_script:
-    - pip install tox
+    - pip install tox pytest-html
   stage: tests
@@ -5,4 +5,4 @@
   stage: tests
-  script: tox -e py27
+  script: tox -e py27 -- --html=py3.html --self-contained-html
   artifacts:
     paths:
@@ -7,3 +7,4 @@
   artifacts:
     paths:
+      - py27.html
       - py27-deprecated-warnings.json

templates/tests/py3.yml

 ---
 py3:
   before_script:
-    - pip install tox
+    - pip install tox pytest-html
   stage: tests
@@ -5,7 +5,7 @@
   stage: tests
-  script: tox -e py3 -- --junitxml=report.xml
+  script: tox -e py3 -- --junitxml=report.xml --html=py3.html --self-contained-html
   artifacts:
     when: always
     reports:
       junit: report.xml
     paths:
@@ -7,6 +7,7 @@
   artifacts:
     when: always
     reports:
       junit: report.xml
     paths:
+      - py3.html
       - py3-deprecated-warnings.json